A krill biomass census survey was carried out at two fishing grounds in the South Sandwich and South Orkney Islands areas during a cruise by RV AtlantNIRO in March/April 1990. The survey was conducted in the upper 100 m layer using a modified Isaacs-Kidd trawl. Trawling speed was 3.2 to 3.6 knots. The total krill stock on the poorly studied site off the South Sandwich Islands was assessed at 3.8 million tonnes, most of which was concentrated in the waters of the Weddell Sea. In contrast to this site, the one off the South Orkney Islands is well-established in terms of both research and commercial harvesting. The overall krill stock here was estimated to be 1.1 million tonnes. Most of this stock was concentrated in the south-western part of the Coronation Island shelf.