Human hepatitis A virus (HAV) was isolated directly in cell culture from infected human fecal extracts using techniques developed for in vitro cultivation of the marmoset-adapted CR326 strain of human HAV. A very long incubation was required in first passage, but vigorous cell culture growth, with incubation periods and virus yields similar to those of the CR326 strain that was isolated originally in marmosets, was achieved on serial passage. As with the CR326 strain, there were no evident cytopathic effects. The isolates proved to be HAV virus based on specific activity in serologic tests and by tests for infectiousness in marmosets.