We report on our experience relating to 62 patients with myelodysplastic syndrome (MDS) aged less than 50 years, seen at our Institution and conservatively treated from July 1983 to December 2000. Patients demographics and clinical features at diagnosis were analysed for their prognostic value on survival and on risk of transformation to acute leukaemia. The median age at diagnosis was 43 years (range 21-50). According to FAB criteria there were 30 patients with refractory anaemia (RA), 3 with refractory anaemia with ringed sideroblasts (RARS), 18 with refractory anaemia with excess of blasts (RAEB), 6 with refractory anaemia with excess of blasts in transformation (RAEB-t) and 5 with chronic myelomonocytic leukaemia (CMML). Fifty patients had evaluable cytogenetic analysis: the most frequent karyotypic change was trisomy of chromosome 8 (10%), followed by monosomy 7 (6%); partial chromosome deletions and translocations were also common abnormalities, occurring on the whole in 16% of patients. At a median follow-up of 15 months 19 patients (31%) progressed to acute myeloid leukaemia (AML). From univariate analysis we identified some features, which appeared to be predictive of outcome and risk of transformation to AML. Age above 40 years (p = 0.002) and high risk according to IPSS score (p = 0.002) were found to be predictive for a shorter survival; FAB grouping (p = 0.0001), percentage > 5% of blasts in the bone marrow (p = 0.001) and high risk by IPSS score (p = 0.0003) were found to be predictive for a higher risk of transformation to AML. Presenting features in young MDS patients may identify subjects at higher risk of unfavourable outcome.