To clarify whether the homozygous deletion (DD) genotype of angiotensin-converting enzyme gene ( ACE) is a genetic risk factor for preeclampsia in Japanese women, we performed ACE genotyping in patients with preeclampsia and healthy pregnant women, and analyzed the relationship between preeclampsia and ACE genotype, taking into account some well-known contributing factors for preeclampsia, such as primiparity, positive family history of hypertension, prepregnancy body mass index < 24, and heterozygosity and homozygosity of T235 (MT+TT) genotypes of the angiotensinogen ( AGT) gene. Among all of the subjects, the frequency of the DD genotype was not different between patients with preeclampsia and controls (16% and 12%, respectively). Regarding primiparity, prepregnancy body mass index < 24, and MT+TT genotypes of AGT, no significant differences in the frequency of the DD genotype of ACE were found between patients with preeclampsia and controls, although in a subgroup positive for family history of hypertension, the frequency of the DD genotype tended to be higher in patients with preeclampsia (25%) than in controls (8%; p = 0.061). Carrying the DD genotype may have some influence on the pathogenesis of preeclampsia, perhaps through effects on placental hypoxia or the interaction of hypertensive disease and atherosclerosis, although this influence may not be strong. Additional studies using a larger number of patients and analyses that include other genetic and environmental factors will be necessary to confirm these results.