A non-enveloped icosahedral virus measuring 60 (+/- 5) nm in diameter has been isolated from pike fry (Esox lucius). The isolate is stable to heat, lipid solvent and acid. Iododeoxyuridine has no effect on its replication. Serologically, the virus is related to the major European strains of infectious pancreatic necrosis virus (IPN) Sp and Ab.The isolate is neutralized by normal trout serum and is not pathogenic for trout fry or for young pike. A line of CHSE-214 cells persistently infected with the isolate was established and has been passed 30 times.