PURPOSE: To estimate cure rate following graft rejection in bilateral corneal transplants in Iranian patients with keratoconus and to determine risk factors associated with rejection. METHODS: In this retrospective study, data were compiled from records of patients who had undergone bilateral penetrating keratoplasty (PK) for keratoconus between 1988 and 2007. In order to estimate cure rate in patients with and without corneal vascularization, we adopted the cure rate frailty model with a Bayesian approach. RESULTS: Two hundred and thirty-eight eyes of 119 patients underwent bilateral corneal transplantion for keratoconus, of which 22.7% experienced graft rejections. Cure rates for patients with and without corneal vascularization were 41% and 79% respectively. Cure rate decreased 12% per decade of increase in recipient age. The 1, 5, and 10-year survival of corneal transplants without any graft rejection episodes were 82%, 74%, and 70% respectively. CONCLUSION: The most important risk factor predisposing to rejection in patients undergoing bilateral PK for keratoconus is corneal vascularization. Cure rate for patients without vascularization was high in this data set, indicating that penetrating keratoplasty in keratoconus patients without vascularization is an efficient and reliable procedure.