The diet of the Osprey was studied in two areas of Finland in 1972-74 by analyzing food remains and carcasses found at nests. A total of 914 prey specimens were detected in 47 nests; they were all fish. Abramis fish (mainly bream, A. brama) were the most common prey both in central Finland and on the southwestern coast of Finland, and made up 63% and 40% of the diet, respectively. On the coast, the proportion of predatory fish (pike Esox lucius, and perch Perca fluviatilis) was 35% and fish of the genus Rutilus (mainly roach R. rutilus) 22%. Crucian carp Carassius carassius and rainbow trout Salmo gairdneri also occurred frequently in some inland nests. Prey composition and size did not change during the breeding season in central Finland. The average length of fish was 20-35 cm corresponding to 150-350 g in weight.