The morbidity rates, ++features of lactation formation, and serum and breast milk lysozyme levels were studied in 91 parturients who showed various breast functional activity in the early postpartum period. The highest frequency of postpartum ++pyo-septic diseases was found in females with hyperlactation. There was earlier appearance of foremilk and milk in these females. Healthy mothers with higher breast functional activity exhibited the greatest levels of lysozyme in the milk and marked decreases in its levels in the blood within the first 3 days as compared to those observed in females who had normal or insufficient quantities of milk.