The incidence of ectopic pregnancy has risen substantially during the past two decades, but the aetiology of a third of cases remains unknown. We have used data from a survey of nurses in Paris, France, to examine the relation between ectopic pregnancy and various occupational exposures. We studied two groups of women--operating-theatre staff and nurses from other departments. The women were asked about outcomes of all pregnancies and occupational exposure to anaesthetic gases, formol, ionising radiation, and antineoplastic drugs during the first trimester of pregnancy. Of 734 pregnancies reported, 15 (2%) had been ectopic. In chi-square analysis, there were significant associations (p < 0.02) between ectopic pregnancy and exposure to antineoplastic drugs, the woman's age, and the number of previous pregnancies. Other occupational exposures and working in an operating theatre did not show significant associations. In logistic regression analysis with adjustment for gravidity, the odds ratio (by the exact method) for ectopic pregnancy associated with occupational exposure to antineoplastic drugs was 10.0 (95% CI 2.1-56.2). Because we had only small numbers of ectopic pregnancies, the odds ratios we estimated have wide confidence intervals. Our findings should be confirmed by a larger study specifically designed to investigate the relation between antineoplastic exposure and ectopic pregnancy.