Summary. Aplastic anaemia is a rare but serious disorder with a high morbidity and mortality rate. The causes of aplastic anaemia are, for the most part, unknown. We report on the hypothesis that aplastic anaemia may be caused by occupational and/or environmental exposures to certain chemicals. The UK Aplastic Anaemia Study was an interview-based case-control study covering the whole of Great Britain. Those patients diagnosed between 1 July 1993 and 20 October 1997, aged £75 years and born and diagnosed in the UK were eligible for the study. Two hundred eligible cases of aplastic anaemia were compared with 387 age-and sex-matched controls. A number of occupational exposures showed increases in risk. In a multivariate model of these exposures the odds ratios (ORs) for solvents/ degreasing agents, pesticides and radiation were >2 and statistically significant. Reported chemical treatment of houses within 5 years of diagnosis had a significantly raised risk for adults [OR ¼ 2AE51, 95% confidence interval (CI) 1AE02-12AE01], particularly for woodworm treatment (OR ¼ 5AE1, 95% CI 1AE5-17AE4). This study identified significant risks associated with self-reported exposure to solvents, radiation and pesticides in the workplace. Self-reported chemical treatment of houses was also associated with an increased risk of developing aplastic anaemia, in keeping with previous literature.