Intracavernous self-injection with vasoactive drugs has become a widely accepted treatment for erectile dysfunctions (ED). Sixty-eight patients affected by ED have been followed during long-term (at least 1 year) treatment with intracavernous prostaglandin E1. Each patient underwent a penile dynamic ultrasound examination using a high-definition probe (13 MHz) before and during the treatment. The drop-out rate was 8.8%. An improvement in spontaneous erections was reported by 13% of patients. The onset of fibrotic nodules occurred in three (1.4%) patients. In one of the latter cases the occurrence of nodules could be related to the frequency and dose of the drug administered, whereas in the other two cases no such correlation could be hypothesized. These findings draw attention to this possible side-effect of long-term treatment with PGE1.