Late toxicity and other serious adverse events (SAE) were analysed in the European Organisation for Research and Treatment of Cancer (EORTC) trial 22863. The study evaluated the value of adjuvant endocrine treatment for locally advanced prostate cancer treated with radiotherapy. From 1987 to 1995, 415 patients were randomised. There was long-term toxicity information for 377 patients (91%). Median age was 70 years (range 50-80 years). Median follow-up for late toxicity was 42 months (range 3-136 months). Toxicity was graded according to a modified Radiotherapy and Oncology Group (RTOG) scale. Other late SAE, that was not classified as severe treatment toxicity, but were still life-threatening, were also assessed. There were 72 patients with grade 2, 10 patients with grade 3 and 4 patients with grade 4 toxicity. There were 20 patients with other late SAE, who were grouped according to their relationship to treatment; likely related (n = 1), unrelated (n = 7) and not assessable (n = 12). Although four treatment-related deaths (1%) occurred, grade 3 or 4 late complications were less than 5%.