Infectious pancreatic necrosis virus (IPNV), serotype N1 isolated from scallops Pecten maxjmus in Norway, was propagated and used in both inoculation and bath challenge experiments with scallops in vivo. Although virus titers measured in scallop tissues decreased, depuration of virus was not complete during the experimental periods. TPNV was still detectable 11 mo after injection. The highest virus titer was found in the hepatopancreas, but virus was also detectable in other tissues, as well as in the hemolymph. After a bath challenge, uptake of IPNV was shown. Virus was present in hepatopancreas, gonad, kidney, mantle, gill, rectum and in the hemolymph 1 d after the uptake. The titer was highest in the hepatopancreas where virus was detectable at the end of the experiment. 50 d after challenge. Virus levels in the rectum decreased below detectable levels after Day 30. Titers decreased rapidly in the hemolymph where no virus could be detected after Day 8. Challenges did not result in increased mortality or in clear pathological changes in the scallops. No evidence of viral replication within the scallops was found.