Acoustic estimates of densities of Antarctic krill, Euphausia superba, at South Georgia during 11 austral summers between 1981 and 1998 are presented. Krill density at the island fluctuated widely from year to year over that time, ranging from ≈2 to ≈150 g m^-2(fresh mass). The 1982, 1991 and 1994 austral summer seasons were characterised by particularly low densities of krill (upper 95% confidence limits <15 g m^-2). For five of the summers between 1990 and 1998 it was possible to calculate separate density estimates for northeastern and northwestern South Georgia, and in four of these seasons density was higher to the east.