Early lactation is very demanding on the ovine maternal body and represents a critical stage for development of newborn lambs. Therefore, our study aimed to investigate the composition of sheep’s milk during the initial phase of lactation, when it undergoes the greatest alterations due to adaptation to the changing nutritional needs of lambs. Twenty-one Polish Mountain sheep were assigned to three experimental groups. Milk samples were collected at day 20 (n = 7, L20), 30 (n = 7, L30), and 40 (n = 7, L40) of lactation. Parameters such as fatty acid (FA) profi le, concentrations of orotic acid (OA), malondialdehyde (MDA), total cholesterol (Ch) and selected chemical forms of vitamin E were determined using gas and liquid chromatography methods. Multivariate statistical analysis was used to detect subtle changes in milk composition between short sampling intervals. FA profi le analysis revealed that the L30 samples were characterised by the highest content of all examined FA. The most abundant were palmitic, stearic, oleic, linoleic, rumenic, α-linolenic, γ-linolenic, and eicosapentaenoic acids. The highest levels of Ch and MDA were recorded in the L20 samples, while OA was predominant in milk from the L30 group. No signifi cant differences in tocopherols content were found at individual lactation days. The research allowed to conclude that milk of Polish Mountain sheep has a nutritionally benefi cial composition, especially in the early lactation stage, which can support the proper growth of lambs.