To determine major presenting features of chronic myeloid leukaemia (CML) in current practice, we have reviewed the records of 430 patients with CML referred to the Hammersmith Hospital for allogeneic bone marrow transplantation since 1981. Approximately 20% of cases were diagnosed incidentally. Symptoms such as fatigue and weight loss were associated with greater degrees of leucocytosis and splenomegaly and lower haemoglobin levels. Most bleeding patients had normal or elevated platelet counts, suggesting that platelet dysfunction was the primary cause of haemorrhage. Although thrombocytosis was common, thrombosis was not seen. Male patients and the relatively young presented with higher WBC counts and larger spleens. The reason that these groups were diagnosed with more advanced leukaemia is not clear. Although retrospective and limited to a select group of relatively young patients, this is the largest series to be reported on CML at diagnosis, and the first such report in modern clinical practice.