Within a period of 3 1/2 years, 101 patients with drug-induced priapism lasting more than 6 h were observed. In 73 of the 101 patients (average age 47.4 years) with an average duration of priapism of 11.9 h priapism was interrupted by means including cavernosal puncture, evacuation, and injection of metaraminol. In 28 patients priapism subsided after an average duration of 8.8 h without medical intervention. Intracavernous blood gas analyses revealed unphysiological acid values with clearly negative excess base values. Nevertheless, in the present series only 3 patients had irreversible damage of cavernosal function as a sequela of priapism of more than 24 h duration. Intracavernosal injection of meta-ramininol was followed by severe hypertensive crisis in 2 patients. These results show convincingly that the demand for early interruption of drug-induced priapism within a time limit of 6 h is not based on objective necessity. Interruption of drug-induced priapism within 6-8 h seems to be adequate. Prostaglandin E1 has proved a reliable means of preventing priapism in the initial test period.