A prevalence survey of anticardiolipin antibodies (aCL) was done among 924 primiparae. aCL were measured in serum by the standardised anticardiolipin enzyme linked immunosorbent assays (ELISA) and beta(2)-glycoprotein 1 assays to determine the seroprevalence of both beta(2) glycoprotein 1 dependent aCL and beta(2)-glycoprotein 1 independent aCL in Jamaican primiparae, to determine whether aCL are associated with abnormal pregnancy outcomes and if treatment with aspirin had any effect on pregnancy outcome in aCL positive primiparae. The prevalence of aCL was (32/671) 4.8% (95%CI 3.2-6.4) in women who were tested twice. A total of 49 of 924 primiparae or 5.3% (95%CI 3.9-6.7) were positive for aCL on at least one occasion. Only three of the 32 primiparae 3/32 (9.4%) who were positive for aCL on two occasions were positive for beta(2)-glycoprotein 1 dependent aCL. Pregnancy outcome did not differ significantly with respect to aCL status. Aspirin therapy did not influence pregnancy outcome in the 49 aCL positive primiparae studied.