We respectfully dissent. In support of their summary judgment motion, defendants submitted the deposition testimony of plaintiff that she did not know what caused her to fall; that her foot did not slip; that she did not trip or stub her toe; and that she could not remember whether she “missed a step.” Contrary to the conclusion of the majority, that evidence is sufficient to establish defendants’ entitlement to summary judgment dismissing the complaint, because it “ demonstrates] that any determination as to what caused the plaintiff to fall would be based on speculation” (Koller v Leone, 299 AD2d 396, 397 [2002]; see Curran v Esposito, 308 AD2d 428, 429 [2003]; Zimmerman v Yuskevich, 306 AD2d 403 [2003]; see also Novoni v La Parma Corp., 278 AD2d 393 [2000]). Contrary to the further conclusion of the majority, the affidavit of plaintiffs expert does not raise an issue of fact whether the alleged building code violation was a proximate cause of plaintiffs fall. Rather, the expert’s assertion that the out-of-level stair treads may have contributed to plaintiffs fall “was not based on admissible evidence in the record, was purely speculative, and was insufficient to raise a triable issue of fact” (Koller, 299 AD2d at 397; see Curran, 308 AD2d at 429; see also Bitterman v Grotyohann, 295 AD2d 383, 384 [2002]; cf. Feldman *987v Dombrowsky, 288 AD2d 605, 606 [2001]). We would therefore reverse the order, grant defendants’ motion and dismiss the complaint. Present—Pigott, Jr., P.J., Green, Hurlbutt, Gorski and Lawton, JJ.