Total count (TC) of bacteria in drifting annual pack-ice in austral spring fluctuated between 2.8-106 and 2,09-109 dm3. TC of bacteria was lowest in the upper layer of a large pack-ice fragment, emersed above water surface and almost completely free of diatoms; it was comparable to TC of bacteria in surrounding sea water, which was very low at this time (1,92- 106 — 5.8-106 dm -3). TC of bacteria increased in the deeper layers of pack-ice, attaining a maximum in the middle layer characterized by a high count of diatoms. TC of bacteria was highest in small pack-ice pieces 10—20 kg in being and densely overgrown with diatoms. Bacterial population in pack-ice was dominated by rods (62%), and it contained filamentous bacteria (2.4%) and prosthecate forms (4,8%), rarely present in deep sea. Mean volume of bacterial cell (0,206/μm3) was small, only slightly exceeding that of cells of free-living bacteria in sea water in summer.