Forty-seven multiparous sows were divided into two groups: control (24) and experimental (23). The sows in the experimental group received a supplement of 50 mg L-carnitine per 1 kg of the diet during pregnancy and lactation. Blood samples were obtained from 8 sows of each group on the 21 and 110 day of pregnancy and 21 day of lactation. Glucose, total protein and cholesterol, HDL-cholesterol and triglycerides (TG) were determined. The results showed that the addition of L-carnitine to the diet significantly contributed to increasing in the piglets’ weaning weight at 21 days of age and the level of HDL-cholesterol, as well as decreasing piglet losses and TG content in blood plasma.