Evidence is presented for the first time that a human candidate calicivirus (HCV) replicates in human embryo kidney cells when trypsin is incorporated in the culture medium. The virus multiplies in the presence of actinomycin D and radiolabelling experiments with [3H]uridine indicate that it has an RNA genome. These observations provide further support for the view that HCV should be tentatively classified as a member of the Caliciviridae .