The migration pattern of Illex argentinus in the waters off Argentina was estimated based on the data collected by research survey from April 1978 to April 1979 and on fisheries statistics of Japanese commercial vessels. In spring of the Southern Hemisphere juvenile squid appear in the northern half of the Patagonian Shelf excluding the area covered by the coastal waters. They disperse gradually towards offshore and southern waters, and spread their habitat to almost the entire shelf by summer. In autumn they move towards the east (the edge of the shelf) and north and aggregate on the slope of 400-700m in depth for some time in the north and middle parts of the shelf. Then they leave the slope probably for spawning in winter.