Hepatitis A virus in feces remained viable after being dried and then stored at 25 degrees C and 42% relative humidity for 30 days, as evidenced by infection of two marmosets inoculated with 1 ml of the treated fecal material. The virus was excreted in stool specimens from these animals, and seroconversion to antibody to hepatitis A virus occurred 28 and 35 days post-inoculation.