PIP: The effect of the 3-monthly injectable contraceptive depot medroxyporgesterone acetate (DMPA) on liver function and lipids was assessed in Thai women both with and without liver fluke (Ophisthorchis viverrini) infestation. DMPA administration was started in the immediate postpartum period and women who accepted immediate postpartum IUD insertion of sterilization were recruited as a control group. Complete 18-month followup results were obtained for 108 DMPA and 106 control fluke-positive subjects and for 89 DMPA and 74 fluke-negative subjects. No woman in any of the groups developed signs or symptoms of hepatic disease and the DMPA users had fewer health-related complaints during followup than the control subjects. Over 80% of both groups of users were amenorrheic 18 months postpartum, compared with about 15% of those in the control group. A large majority of subjects in each group continued to breastfeed for the entire study period without complaint. Weight change was small and similar in both the DMPA and control groups. Total bilirubin, aspartate aminotransferase, alanine aminotransferase, dehydrogenase, and alkaline phosphatase levels at 6, 12, and 18 months in the DMPA groups were generally equivalent to or lower than those in the corresponding control groups. Cholesterol levels were significantly decreased in the fluke-positive DMPA subjects while serum triglycerides were significantly decreased in both DMPA groups compared with their controls throughout the followup period. We conclude that during 18 months of use, DMPA did not cause any deleterious effects on health or on the metabolic factors studied in women with and without liver fluke infestation.