We describe a surgical arthroscopic treatment for popliteal cyst in a series of 30 patients, with a mean follow-up of 32 months. The treatment consists of a cure for the intra-articular pathology of the knee associated with popliteal cysts, and the contemporaneous correction of the valvular mechanism responsible for the formation and reoccurrence of popliteal cyst. The popliteal cyst in adults was found to be almost invariably associated with other knee disorders. In all of the cases studied, a connection between joint space and cyst was found. Arthroscopy allowed the treatment of almost all of the associated knee disorders and the removal of anatomic structures imposing the one-way passage of fluid from the joint space into the cyst. Two years after the treatment, we observed optimal or good clinical results in 95% of the patients treated.