BACKGROUND There is little data available on the occurrence of leukaemias in India. This is despite a large number of patients being diagnosed and treated at various cancer centres all over the country. We, therefore, analysed the available data of the Bombay Cancer Registry to ascertain the epidemiological characteristics of leukaemias in India. METHODS The incidence and mortality rates of leukaemias by cell type and sex were obtained for the most recent 5 years (1989-93). The data of the past 30 years were used to study the time trends using a linear regression model based on the logarithms of the incidence rates. RESULTS Leukaemias constituted 3.9% of all registered cancer cases and 5.4% of all registered deaths in Greater Mumbai. Males were affected more frequently than females. Myeloid leukaemias were the commonest. A bimodal age incidence was observed with the first peak in childhood, a trough between 15 to 19 years of age and a slow rise thereafter. Among the various religious groups Hindus had the highest rate. An increasing trend in the incidence of all types of leukaemias was also observed. CONCLUSIONS The incidence of leukaemias in Greater Mumbai is comparable to world rates. There is a male preponderance in all cell types and an increase in incidence was observed over the last 30 years. The higher incidence of myeloid leukaemias observed by us might be related to under-reporting of chronic lymphatic leukaemia.