Selenium (Se) is a micronutrient that is responsible for regulating immune, antioxidant, and reproductive processes in the body. Selenitetriglycerides are a novel, organic form of Se; to date, the effects of selenitetriglyceride supplementation have been studied only in ruminants. The aim of this study was to determine the effect of selenitetriglycerides administered to sows before parturition on Se concentration and selected hematological and biochemical parameters, and to evaluate the efficacy of selenitetriglyceride supplementation in preventing Se deficiency in sows and piglets. The study was conducted on 12 pregnant sows and their offspring. The control group consisted of sows that did not receive the selenitetriglyceride supplement, and their offspring. The experimental group consisted of sows that were orally administered a selenitetriglyceride supplement at 0.5 mg Se kg^-1 BW, 15, 10, 5, and 3 days before the parturition date, and their offspring. Blood samples for analyses of Se concentration, morphological parameters, selected biochemical parameters (AST, ALT, TP, ALB, UREA, CREA), and GSH-Px activity were collected from sows 15, 10, 5, and 3 days before parturition and 2 days postpartum. Blood samples for analyses of Se concentration were collected from 3-, 5-, 10-, and 15-day-old piglets. No significant differences in hematological or biochemical parameters were observed between the groups of sows. Beginning on the fifth day of the experiment, Se concentration and GSH-Px activity were significantly higher in experimental than control group sows. During the entire experiment, Se levels were significantly higher in experimental than control group piglets. The results of the study indicate that selenitetriglycerides are a safe and effective source of Se for pigs. Selenitetriglycerides are effectively transferred to offspring with the mother's milk and colostrum, and they can be administered to prevent Se deficiency in pigs.