Moxisylyte chlorhydrate is a selective alpha-blocker of the post-synaptic alpha 1-adrenoreceptors. It has been used since 1992 for self-injections to induce erection. Tolerance has been studied in open trials in 143 men using 20 mg per intracavernous injection. Among these subjects, 104 were followed for 11 months. Self-administration was performed 7,509 times, i.e. 49.1 injections per subject over a mean period of 307 days. No severe side effects were observed. A total of 1,041 undesirable effects were reported by 90 subjects (75.1%), including mechanical disorders (28.2%) such as pain and burning sensation at injection, hematomas and ecchymoses. Nodules developed in 0.08% of these cases but always regressed. In 71.8% of the cases, the undesirable events was imputable to moxisylyte: dry mouth (2.73%), somnolence (1.9%), sinus congestion (0.71%). No case of priapism was reported. Long-term evaluation showed a reduction in the main undesirable effects with time. This fall off in the mechanical events could be explained by the subjects become for familiar with the technique. Pharmacological effects remain to be analysed. Added to the good tolerance, this result suggests that self-injection can be proposed as a first intention treatment for impotency.