Sydney Rock Oysters, when allowed to feed in waters containing approximately 10(4) cfu of Campylobacter cells per ml, concentrated between 10(2) and 10(3) cfu of the organism per g of oyster tissue, within 1 h. When these contaminated oysters were subjected to depuration, they were effectively cleaned in 48 h. The survival of Campylobacter jejuni and Campylobacter coli was also investigated. Oysters contaminated by feeding and injection were processed as half shells and bottled oysters and were held at 3 and 10 degrees C. Half shells were also stored at -20 to -24 degrees C. At all these temperatures the organism survived for periods varying between 8 to 14 days and in oysters contaminated by feeding, the survival was substantially greater. Survival was better at 3 than at 10 degrees C in half-shelled oysters. Campylobacter survived better in bottled oysters than in half shells stored at the same temperature. In frozen half shelled oysters previously contaminated by feeding, the organisms were viable for months. In contaminated unopened oysters stored at 20 and 30 degrees C, C. jejuni and C. coli failed to multiply as expected. They survived for periods varying from 2 to 9 days.