In 72 consecutive patients with previously untreated myelodysplastic syndromes (MDS) having a median follow-up of 44.9 (range: 6-198) months, a multiple regression analysis was conducted of the prognosis significance of 26 clinical and laboratory parameters, including bone marrow (BM) biopsy characteristics. Parameters which had independent prognostic meaning served to construct a scoring system for survival prediction. Only 7 parameters were significant: hemoglobin, BM cellularity, BM blast percentage, abnormal location of immature precursors (ALIP), fibrosis, dysmegakaryopoiesis and the erythro/myeloid ratio. They enabled us to predict 42% of all MDS patient survival (p less than 0.03) and 84% (p less than 0.02) of survival of patients who lived over 20 months. Based on the value of these parameters in individual cases, the patient population had a score ranging from 0 to 13, with a median value of 5. Median survival of patients with a score less than or equal to 5 was 117, while that of patients with a score greater than 6 was 33 mos. This scoring system, which has been draw from a wide panel of clinical and laboratory parameters, will be verified on prospective studies.