Serum samples from 176 brown hares (Lepus europaeus P.) shot in three areas of south and central Sweden during 1984 and 1985 were analyzed for antibodies to the protozoan parasite Toxoplasma gondii using several serological assays. No toxoplasma antibodies were detected in any of the sera, either by direct agglutination test or by ELISA, and selected sera were also negative in the IFAT and the Sabin Feldman dye test. Based on the high incidence of acute fatal toxoplasmosis in hares in Scandinavia, we propose that the brown hare is exceptionally susceptible to primary T. gondii infection.