Six surveillance spots were set up in Jiaozhou Bay to examine the contamination of Ruditapes Philippinarum (R. P) by HAV. Specimens were collected regularly every month. Seventy-five specimens were collected in July 1991-Aug 1992. The precursor RNA of HAV was detected by methods of PCR, RNA dot-blot hybridization and HAV isolation. It showed that R. P. had been contaminated by HAV in some areas of the bay at times, but the virus was in a state of inactivity. Epidemiologic investigation in the same period proved that R. P. was not the direct cause of HA epidemic in Qingdao. However, the domestic sewage is directly drained into the Jiao zhou Bay so the control of the city sewage drainage system must be enforced and health education serve for people in taking sea food and drink should be strengthened.