This is a review of a decision of the Benefits Review Board affirming an administrative law judge’s award of black lung benefits pursuant to the Black Lung Benefits Act, 30 U.S.C. § 901 et seq. Because the ALJ and the Board applied the wrong standard in evaluating the evidence, we must remand the case for redetermination.
To receive black lung benefits, a claimant must show that he is totally disabled due to pneumoconiosis that arose out of coal mine employment. See 20 C.F.R. §§ 727.-201-.202 (1982). To aid the claimant in his proof, the regulations provide certain presumptions which, if available, establish his entitlement to benefits unless rebutted by the employer. See id. § 727-203. The issue in this case is whether, in finding in favor of the claimant, the ALJ properly invoked the presumption under § 727.-203(a)(4).
At a hearing before the ALJ, evidence was presented by both the claimant and his employer. The evidence included x-ray readings, pulmonary function studies, and arterial blood gas studies. It is undisputed that much of the evidence is contradictory. For example, there were conflicting opinions as a result of x-rays. The issue this review centers around is the fact that at least two physicians concluded that the claimant was not totally disabled as a result of pneumoconiosis, but at least one physician’s conclusion was to the contrary.
In finding for the claimant, the ALJ invoked the presumption provided in § 727.-203(a)(4).1 Under this provision, a claimant is presumed to have coal worker’s pneumoconiosis if “[ojther medical evidence, including the documented opinion of a physician exercising reasoned medical judgment, establishes the presence of a totally disabling respiratory or pulmonary impairment.” The ALJ, however, invoked the presumption solely on the basis of one physician’s opinion, reasoning that the documented and reasoned opinion of one physician alone requires the invocation of the presumption under (a)(4) regardless of the existence of, and without weighing, other contrary evidence. The Benefits Review Board affirmed the ALJ’s determination.2
Invocation of the § 727.203(a)(4) presumption solely on the basis of one physician’s opinion, without weighing it against other physicians’ contrary opinions, is contrary to our holdings in Sharpless v. Califano, 585 F.2d 664 (4th Cir.1978), and Petry v. Califano, 577 F.2d 860 (4th Cir.1978). Sharpless and Petry involved the similar presumptions of total disability due to coal worker’s pneumoconiosis provided for in 20 C.F.R. §§ 419.490(b) and 410.414(b), respectively. In both cases we held that the *482claimant has the burden of proving by a preponderance of the evidence all the facts necessary to establish the presumption. 585 F.2d at 667; 577 F.2d at 864; see Steadman v. SEC, 450 U.S. 91, 101 S.Ct. 999, 67 L.Ed.2d 69 (1981). Our cases require the administrative tribunal to weigh all the evidence relevant to a fact necessary to establish a presumption before deciding to invoke the presumption. 585 F.2d at 667; 577 F.2d at 863. We note in passing that in cases involving at least two of the other presumptions set out in § 727.203(a) the Board itself has held that an ALJ must consider and weigh all the competent and relevant evidence bearing on the fact in question in determining whether to invoke the presumptions. See Justice v. Jewell Ridge Coal Corp., 3 Black Lung Rep. 1-547, 1-550 (1981) (§ 727.203(a)(1)) (x-rays); Strako v. Zeigler Coal Co., 3 Black Lung Rep. 1-136, 1-143 (1981) (§ 727.203(a)(2) (ventilatory tests)).
To repeat, the presumption in question provides that a miner who has been engaged in coal mine employment for at least 10 years will be presumed to be totally disabled due to pneumoconiosis if the following medical requirement is met:
(4) Other medical evidence, including the documented opinion of a physician exercising reasoned medical judgment, establishes the presence of a totally disabling respiratory or pulmonary impairment; § 727.203(a)(4).
We are of opinion it was error for the ALJ and the Board to hold that the mere existence of one such documented opinion required the invocation of the presumption without considering all the other evidence, including the other and contrary documented opinions. The regulations in terms require that “other medical evidence,” including the physician’s opinion, must establish the presence of a totally disabling respiratory or pulmonary impairment. It is the obligation of the ALJ and the Board to ascertain if such is so established. Leaving aside for the moment other evidence outside the written opinions, when, as in this case, there are at least three physicians’ opinions, two of which state there is no such totally disabling impairment and one of which states that there is, then it is the obligation of the administrative tribunal to ascertain whether or not the claimant has established the presence of the impairment by a preponderance of the evidence, and in so doing to consider and weigh all three opinions.3 The mere existence of one such opinion in the circumstances present here is insufficient to require the invocation of the presumption.
The order being reviewed must be vacated and the case remanded for action not inconsistent with this opinion.
VACATED AND REMANDED.4
. The ALJ found that the pulmonary function and blood gas studies were insufficient to invoke the presumptions provided for in §§ 727.-203(a)(2) and (a)(3). He further specifically did not resolve the conflicting evidence of x-ray findings, so that § 727.203(a)(1) did not apply, there having been no biopsy.
. In its decision and order, the Board relied in part upon Stiner v. Bethlehem Mines Corp., 3 Black Lung Rep. 1-487 (1981). Consistently with the ALJ’s reasoning, a divided Administrative Appeals panel, in Stiner, rejected a weighing of all the evidence in determining whether to invoke the presumption under § 727.-203(a)(4). Id. at 1-490. Rather, Stiner held that a single reasoned medical opinion that there is a totally disabling respiratory or pulmonary impairment requires the invocation of the presumption. Id.
. With respect to the dissenting opinion, we think that it is written with a different understanding of the administrative decision than that which we hold.
The dissenting opinion is based on the proposition that “the reasoned opinion of a single physician is sufficient evidence to invoke the presumption,” p. 483.
The administrative opinion which we review holds that “the mere existence of one such documented opinion required the invocation of the presumption.” SI. op. p. 5. We do not quarrel with the proposition that a single opinion of a physician may be sufficient to invoke the presumption. What we do say is that one such opinion in the presence of other and contrary evidence may not require the presumption to be invoked, absent a weighing of the opinion against the other evidence.
. It follows that the motion of the respondent Sanati to dismiss the appeal is denied.