The Sorbinil Retinopathy Trial (SRT) was a unique collaboration between private industry and the Federal government in designing, funding, and conducting a multicenter, randomized clinical trial. Pfizer Inc. supported 10 of the 11 participating Clinical Centers, provided the medication, and funded the Data Coordinating Center and Fundus Photograph Reading Center. The National Eye Institute funded the Policy, Data, and Safety Monitoring Committee and its own participating Clinical Center.