Between September 1983 and January 1990, 64 patients with Klatskin tumors were treated with resective therapy in the Academic Medical Centre Amsterdam. Twenty-nine patients received postoperative adjuvant radiotherapy, 22 patients were treated with resective therapy only and there were 13 postoperative deaths. The longterm results in the patients treated with or without adjuvant radiotherapy were retrospectively assessed. Three patients had a curative resection. Comparison of both therapeutic modalities demonstrated a statistically significant difference in survival (P less than 0.001) in favour of the patients who were treated with additive radiotherapy. The radiotherapy was generally well tolerated.