We reviewed the medical records of 103 consecutive cases of vitrectomy performed for complications of diabetic retinopathy to determine if the introduction of argon laser endophotocoagulation had reduced the incidence of recurrent vitreous hemorrhage. Twenty-six eyes (48%) treated with endophotocoagulation and 35 (71%) eyes not receiving laser treatment had a recurrent hemorrhage. Follow-up was shorter for the eyes treated with endophotocoagulation, but a log-rank analysis to allow for this variable confirmed the benefit of laser photocoagulation (P less than .05). The proportion of eyes requiring surgical removal of the hemorrhage was also significantly lower in the group receiving endophotocoagulation (P less than .05). The beneficial effect of intraoperative laser treatment was independent of the amount of preoperative laser treatment, aphakia, and indications for the original vitrectomy surgery.