dissents in a memorandum as follows: The majority reverses and orders a new trial upon the ground that defendant was surprised by the introduction of a new theory of liability into the case at a time when the defendant was prepared only on a different theory. It cannot be disputed a trial is manifestly unfair when a party is suddenly called upon to defend on a theory belatedly brought into the case, one completely foreign to that claimed in the bill of particulars, and which is completely without notice or opportunity to prepare to meet it. But the plea of surprise should be based on actual surprise, not merely deficiencies in pleading. In essence the majority’s ruling is that plaintiffs motion to amend her complaint and bill of particulars after both sides had rested should have been denied. Plaintiff says the majority, was permitted to inject into the case for the first time a new theory of liability that defendant, knowing of plaintiffs internal condition, should not have referred her for the hysterosalpingogram because such a procedure is medically contraindicated in the presence of abdominal infection, due to the irritating quality of the radio-opaque substance injected, and was the cause of the flare-up which followed this procedure, thus constituting malpractice. It is true that such specific claim is not asserted either in the complaint or in the bill of particulars. However, it is equally true that relatively early in the trial, during the cross-examination of plaintiffs witness, Dr. Stanley West, defendant’s attorney asked Dr. West a series of questions injecting the hysterosalpingogram theory into the case for the first time and attempting to establish that all of the subsequently experienced symptoms of the patient were due to the hysterosalpingogram. Defendant’s plain purpose was to show that this procedure was at least in part the source of plaintiffs problems. It is true that thereafter plaintiffs witness, Dr. Louis Gentile, similarly testified. That the defendant was prepared to deal with this problem is clear from his examination of Dr. Calem, defendant’s first witness, in which that doctor asserted that he had made the decision as to subjecting plaintiff to the hysterosalpingogram. It is *507plain that the case was tried upon this theory of liability and that the defendant was fully aware of this theory and tried his case on that basis. At the end of plaintiff's case her counsel moved to amend the pleadings to conform to the proof to permit the jury to rule on whether the defendant "erred in ordering a hysterosalpingogram”. Although the court reserved decision, it denied defendant’s motion to exclude this theory on the ground that it was not encompassed within the bill of particulars. As the court noted, this subject matter and theory had been litigated before the jury for at least a week. Defendant then interposed expert testimony that ordering the hysterosalpingogram was not malpractice and called the doctor who had actually performed the procedure and assumed the responsibility for it. As the Trial Judge noted, "I am inclined to believe that this was no surprise, this is a matter which the defendant had ample opportunity to consider and did consider with both Dr. Calem and Dr. Birnbaum, who advised the defendant over a year ago. I don’t find any surprise and I don’t find there is any prejudice. Accordingly the application to amend the bill of particulars to include the allegation that Dr. Davidson should have palpated the mass and operated, instead of ordering a hysterosalpingogram, is granted.” The barrier to the amendment of bills of particulars and pleadings is prejudice. When no prejudice is shown the amendment is proper during or even after trial (Murray v City of New York, 43 NY2d 400; Dittmar Explosives v A. E. Ottaviano, Inc., 20 NY2d 498). When a variance develops between a pleading and proof, amendment should be granted unless prejudice is plainly shown. On this record there is no such prejudice. The defendant had a full and fair opportunity to defend against the claim which was made early enough on the trial to alert defendant as to its nature. Defendant skillfully defended against the claim. His witnesses fully testified on the issue and plaintiff and her witnesses were thoroughly cross-examined with respect to it. Any surprise is purely formal. There was no actual prejudice. The judgment appealed from should be affirmed, with costs.