This study determined hexachlorobenzene (HCB) levels in the blood of women who had suffered spontaneous abortions (120 cases) and women with healthy reproductive functions (120 controls). Samples were collected in 1984 during an epidemiological investigation into the relation between polychlorobiphenyl levels in the blood and spontaneous abortion in the women. Evaluation of the HCB data showed no significant differences between the groups, the blood of the group with spontaneous abortion containing 1.6 +/- 1.6 ppb HCB compared with 1.5 +/- 1.1 ppb for the control group.