Paraoxonase 1 (PON1) is thought to influence serum homocysteine concentrations, at least in part, due to its homocysteine thiolactonase activity and to play a role in preeclampsia and atherosclerosis. We investigated the effects of PON 55 and PON 192 polymorphisms on plasma total homocysteine (tHcy) concentrations in preeclamptic and healthy pregnants among Turkish population (N = 106). PON 55 and 192 genotypes were determined by PCR RFLP techniques. Plasma tHcy concentrations were measured by high-performance liquid chromatography. No differences were observed in the distribution of PON1 55/192 genotypes and allele frequencies between the preeclamptic and health), pregnants. tHcy level in the plasma of preeclamptic women was found to be increased in comparison with health), pregnants (P < 0.01). Preeclamptic women bearing the mutated PON 192RR and wild-type PON1 55LL genotypes had higher tHcy levels than those of the healthy pregnants with the corresponding genotypes, supporting the possibility that the hyperhomocysteinaemia seen in preeclamptic women is associated with the PON genotypes. However, no influence of the allelic distribution on plasma tHcy concentrations was detected in either group. Our results suggest that PON1 55 and 192 genotypes might have an important role in developing hyperhomocysteinaemia and may also have a role in the pathogenesis of preeclampsia in a Turkish population.