Summary. The present study applied the International Prognostic Scoring System (IPSS) to 306 consecutive myelodysplastic syndrome (MDS) patients diagnosed between August 1977 and September 2000 at the University Medical Centre Nijmegen. The aim was to investigate whether the IPSS could be used as a prognostic tool in MDS patients aged less than 61 years who were treated with acute myeloid leukaemia (AML)-like chemotherapy with or without transplantation, and whether the scoring system discriminated between the subgroups of patients who benefit from intensive treatment strategies. The patients were retrospectively assigned to the IPSS risk categories and compared with the IPSS workshop patients. Eighty-three of 159 patients aged < 61 years, classified as intermediate 1, intermediate 2 and high risk according to the IPSS, received intensive treatment consisting of chemotherapy only (n = 30), chemotherapy followed by either autologous stem cell transplantation (n = 7) or allogeneic stem cell transplantation (n = 46). After intensive treatment, the median survival was 2·6 years for the intermediate 1 risk group (n = 33), 3·4 years for the intermediate 2 risk group (n = 27) and 0·9 years for the high-risk group (n = 23). We conclude that the IPSS is an improved scoring system for patients receiving supportive care. Nevertheless, the scoring system does not seem to be the best method for predicting outcome after intensive antileukaemic treatment. In particular, intermediate 2 risk patients may benefit from intensive treatment.