In 1998 the 2nd Ukrainian Marine Complex Antarctic Expedition (UMCAE) on board scientific research vessel "Ernst Krenkel" took place in the western part of the Atlantic sector of the Antarctic. It was arranged by the Ukrainian Antarctic Center of the Ministry for Affairs of Science and Technologies of Ukraine. The preliminary analysis of the data compiled allows revealing some specific features of the environmental conditions, state of the krill population, other functionally important components in the pelagic ecosystems of the areas under review. In Subarea 48.2 there were fixed water low temperatures and great amount of icebergs (together all these factors characterize the navigational season of 1998 as abnormally cold), recruitment of the stock (for the first time for recent years), low abundance of krill larvae, plenty of salps (their abundance and biomass occurred to be higher 1.6 times than the same indices for 1997). In Subarea 48.1 there were revealed the differences in size composition of krill and in its biomass on the fishing sites near the Elephant Island and the King George Island. In the former of them the basis of catches comprises krill of the third size group (evidently, generation of 1995); in the latter - krill of the second and third group with the evident share of the recruitment group.