The purpose of this study was to determine the changes in serum cholesterol, triglyceride, urea, creatinine, glucose, uric acid, calcium, total protein and albumin levels during late pregnancy, parturition and early lactation periods in mares. Eighteen pregnant thoroughbred Arabian race mares from 5 to 15 years of age were included in the study. The mares were fed 2.4 kg concentrate and hay ad libitum daily. Blood samples were taken from the jugular vein on 45, 30 and 15 days before parturition, at parturition and on 3, 10, 15, 22, 28, 35 and 45 days thereafter. Serum samples were stored at -20 degreesC and analyzed within one week. Serum cholesterol, triglyceride, urea, creatinine, glucose, uric acid, calcium, total protein and albumin levels were determined by commercial kits using an autoanalyser. Serum cholesterol level rose at parturition (p<0.05) and lowered after parturition. Serum triglyceride levels were high during late pregnancy and diminished after parturition. Serum creatinine levels were higher during late pregnancy than early lactation (p<0.05). On the other hand, serum urea, glucose, uric acid, calcium, total protein and albumin levels were not statistically different between the periods. The results indicate that the lipid metabolism of late pregnant mares is affected because of energy demands of the growing fetus.