In the process of bud break in downy birch Betula pubescens Ehrh., silver birch Betula pendula Roth, and Karelian birch Betula pendula var. carelica Merckl., total lipid (TL) content in buds varied within 27–45 % of absolute dry weight (a. d. w.). The chief TL fraction was neutral lipids, contributing up to 42 % of a. d. w., whereas glyco- and phospholipids did not exceed 13 and 8 %, respectively. Unsaturated FA in birch buds contributed up to 85 % to total FA. They were primarily represented by linoleic and linolenic acids (up to 44 and 39 % of total FA, respectively). The most abundant saturated FA was palmitic acid (up to 32 %). Linoleic acid content declined further into the bud break period. Species-specific features of the lipid composition of breaking buds in the birches were identified.