Despite the high frequency of pregnancies complicated by abnormal glucose metabolism associated with obesity, methylmercury (MeHg) metabolism in pregnant women with abnormal glucose metabolism is unclear. We aimed to elucidate the MeHg tissue distribution in obese female mice with abnormal glucose metabolism and their fetuses. Female C57BL/6J mice were fed a high-fat diet (HFD) or a standard diet (Ctrl) for 12 weeks and mated. HFD mice showed mild glucose metabolism abnormalities as assessed by an oral glucose tolerance test. Maternal tissues (brain, liver, and kidney) and blood (plasma and blood cells) and fetal tissues (brain, liver, kidney, and placenta) were collected from these mice 24 h after oral administration of MeHg (a single dose of 1 or 5 mg Hg/kg) on Day 16 of mating. The total mercury level was determined in each sample, and its distribution to each tissue was estimated using K