Thé following observations resulted from studies on forensic autopsy cases: In 76% of the adults and 55% of the infants the cases of unexpected sudden death without morphologically verifiable causes of death showed virologic evidence of recent influenza-A (H3N2)-infection. The pathologic findings corresponded with the findings in lethal infections with influenza-A viruses. Investigation of cases of sudden and unexpected death should always include virologic serum tests. The demonstration of IgM antibodies against influenza-A virus confirms that there was a recent infection. Death from influenza-A infections occurs also in the interepidemic periods.