During a three‐year period from 1967–70, 27 of 28 patients operated for ovarian cancer in all stages, including six with metastatic tumours in the ovaries, have been treated post‐operatively with Treosulfan. Clinically, the non‐radically operated patients improved considerably for varying periods. In the radically operated patients treated immediately with Treosulfan, we have not yet seen any recurrence. Apart from marrow depression, the drug has shown very few side effects. Subjectively, all patients have been more comfortable during tr