Summary. We have studied the clinical and laboratory features of 53 cases of chronic myelomonocytic leukaemia (CMML) defined according to the FAB criteria. A granulocyte count of < 16 x 109/l or a monocyte count of < 2.6 x 109/l correlated with a poorer survival, but the best predictor of poor survival was the modified ‘Bournemouth’ score in which one point each was allocated for Hb < 10 g/dl, neutrophils < 2.5 x 109/l or > 16 x 109/l, platelets < 100 x 109/l and bone marrow blasts > 5%. A score of 2 or more was predictive of poor survival (Chi2= 10.25; P < 0.001). Those patients with low monocyte and neutrophil counts and a low modified Bournemouth score tended to have a clinical course similar to refractory anaemia (RA) with an indolent course not requiring treatment and long survival whereas those with high monocyte and neutrophil counts and a high modified ‘Bournemouth’ score have a clinical course resembling that of refractory anaemia with excess of blasts (RAEB).