OBJECTIVES: A hospital-based case-control study, the first in India, was conducted to determine the incidence of childhood aplastic anaemia in and around Lucknow in the backdrop of organochlorine levels in the blood and review the database for any association between the disease and exposure to pesticides. DESIGN AND METHODS: A total of 25 cases of childhood aplastic anaemia were identified as per established criteria and enrolled over the study period of 1 year. Their blood organochlorine levels were determined using a gas-liquid chromatograph equipped with an electron capture detector. RESULTS: The annual incidence of childhood aplastic anaemia in and around Lucknow was found to be 6.8 cases per million which is higher than many countries (e.g., France, Brazil, UK, and United States) but lower than those reported in Sweden, China and an European-Israeli collaborative study. Blood levels of alpha-HCH, gamma-HCH, delta-HCH, total-HCH, and p, p'-DDE were higher in children with aplastic anaemia than in those of controls; only alpha-HCH differed significantly (P