Opinion by
Judge MacPhail,Richard Sokol (Petitioner) appeals a decision of the Pennsylvania Workmen’s Compensation Appeal Board (Board) which reversed a referee’s award of benefits.
Petitioner was employed as a prison guard by the State Regional Correctional Facility at Mercer, Pennsylvania (Employer). On January 24, 1981, while bending down to conduct a routine “pat” search of inmates, Petitioner felt a .sharp pain in his back, his left side, and his leg. Petitioner reported this incident to his supervising officer, Lieutenant Harry Wilson. Petitioner also went to the infirmary for medication to relieve his back pain.
Petitioner did not work the next day. On January 26, 1981, PetiiioDer was admitted to Sharon General Hospital Avith a diagnosis of a ruptured intervertebral disc. Shortly thereafter, Petitioner undemvent a myelogram, a laminectomy and discectomy.
On April 2, 1981, Petitioner filed a claim for compensation and after a hearing, the .referee found that Petitioner had sustained an injury during the course of his employment and .awarded benefits. The Employer appealed, arguing that Petitioner had not established a causal connection between the injury and his work with unequivocal medical evidence. The Board sustained Employer’s appeal and reversed the *399referee’s award of benefits. The instant appeal ensued.
Where there is no obvious causal relationship between an injury and work activity, a workmen’s compensation claimant must establish the causal connection with unequivocal medical testimony in order to recover, Myers v. Workmen’s Compensation Appeal Board (Firestone Tire & Rubber Co.), 67 Pa. Commonwealth Ct. 603, 447 A.2d 1094 (1982), but where a claimant’s disability is obviously and directly the' result of a work incident, medical testimony is not required to establish the causal connection. Hills Department Store v. Workmen’s Compensation Appeal Board (Breon), 73 Pa. Commonwealth Ct. 82, 457 A.2d 226 (1983). We have stated that “ [l]ay testimony is probative on the issue of physical injury and the cause of that injury only if the cause and effect ■are so immediate, direct, and natural to common experience as to obviate any need for expert medical opinion.” Kistler v. Workmen’s Compensation Appeal Board, 54 Pa. Commonwealth Ct. 334, 337, 421 A.2d 500, 501 (1980).
Employer argues here that it is not clear that patting down prisoners involves force or strain and that therefore the Board was correct in holding that in the absence of unequivocal medical testimony, Petitioner had not established that his back injury arose in the course of his employment. Petitioner argues that pain is an excellent symptom of an injury, citing Morgan v. Giant Markets, Inc., 483 Pa. 421, 397 A.2d 415 (1979), and because Petitioner experienced pain when he performed the pat search, the connection between the activity and his injury was obvious.
We believe that this case falls within the rule that where a claimant’s injuries are immediately and directly the result of an accident, medical testimony is not required. Munns v. Easthome Furniture Indus*400tries, Inc., 193 Pa. Superior Ct. 61, 164 A.2d 30 (1960). In Munns, the claimant was using an air gun stapler. As she was doing .her work, claimant twisted or sprained her arm and shortly thereafter felt a numbness in her fingers. Claimant continued to work, but her pain increased to the point where she had .to be admitted.to the hospital. Diagnostic .tests revealed.an injury compatible with a ruptured disc. The claimant had no prior history of back trouble. Although claimant’s treating phpsician’s testimony was not sufficiently, unequivocal to establish the necessary causal connection, compensation was awarded because claimant’s injury was of such nautre as to be the natural and probable result of the accident.
Similarly, in Morgan, the claimant experienced severe back pain when he tried to unload his bakery truck. No medical witnesses testified ,on behalf of this claimant. Our Supreme Court granted compensation benefits, reasoning that “ [wjhere one is doing an act that requires force or strain, the injury may be found to have been established. Pain is an excellent symptom of an injury.” 484 Pa. at 424, 397 A.2d at 417.
In the instant case, Petitioner was performing his job when he immediately felt a sharp pain in his back. Within two days, surgery was determined to be necessary to treat Petitioner’s injury. Under these circumstances, we hold that unequivocal medical testimony is. not necessary to establish what is apparent from the chain of events. Yellow Cab Co. v. Workmen’s Compensation Appeal Board, 37 Pa. Commonwealth Ct. 337, 390 A.2d 880 (1978).
Where the referee’s findings are supported by substantial evidence, and the Board, as here, takes no additional evidence, the referee’s findings must be accepted. Rowan v. Workmen’s Compensation Appeal Board, 58 Pa. Commonwealth Ct. 56, 426 A.2d 1304 (1981). Since we conclude that there is substantial *401evidence to support the referee’s finding that Petitioner had sustained an injury during the course of his employment, we must reverse the Board.
Accordingly, we reverse the Board and reinstate the order of the referee.
Order
The order of the Workmen’s Compensation Appeal Board, No. A-82249, dated February 3, 1983, is hereby reversed.