As of January 6, 1998, a total of 16 confirmed and three suspected cases of human infection with avian influenza A(H5N1) viruses have been identified in Hong Kong. Confirmed cases are those from which an influenza A(H5N1) virus was isolated or in which a seroconversion to influenza A(H5N1) virus was detected by a neutralization assay. Suspected cases are those with influenza-like illness (ILI) and preliminary laboratory evidence of influenza A(H5N1) infection. This report summarizes interim findings from the ongoing epidemiologic and laboratory investigation of influenza A(H5N1) cases by health officials in Hong Kong and by CDC.