From 1970 through 1984, 53 patients with squamous cell carcinoma of the penis have been treated by interstitial irradiation with iridium 192 wires; in this group 33 patients have been followed for at least ten years. There were 7 T1, 31 T2, 15 T3 and 37 N0, 7N1, 6 N2, 3 N3 (WHO classification, 1979). Forty eight patients were treated by interstitial radiotherapy alone, after previous circumcision for 35 of them, and five by an association of external and interstitial radiotherapy. Eleven patients presented a local recurrence; all but one were controlled by penile amputation. Fifteen patients developed severe complications (necrosis, urethral stenoses treated by surgery) and ten of them underwent a secondary total or partial penile amputation. Complications are strongly correlated with the irradiated area and the dose (over 65 grays). Recurrences and complications may develop very late after the treatment, beyond ten years. They required 12 partial and 10 total amputations. Interstitial radiotherapy is the first line treatment for carcinoma of the penis and it is well accepted by the patients. However, to keep a reasonable rate of complications and recurrences we limit the indications of interstitial radiotherapy to the small lesions (T1-T2) and we suggest to decrease the dose under 65 grays. To avoid some local failures we treat now the whole glans.