The objective of this paper is to report a method for estimating the cost of treating acute myelocytic leukaemia (AML). It is based on individual data from 54 patients treated with aggressive induction courses of chemotherapy. The study records the cost of the entire survival period for 40 patients and of at least 16 months' survival for the remaining 14 patients. All treatment activities were registered from the patient records and the price of each activity was estimated. As far as possible the principle of opportunity cost was used. The median survival time was 50 weeks and the average cost per patient was c. 300,000 SEK (= c. USD 50,000) in 1988 prices. A young man who achieved three remissions and lived for five years had the highest cost, c. 1 million SEK (= USD 155,000). The costs for AML treatment was higher in the 1980s than in the 1970s but led to longer survival for patients who survived the initial period.