Little is known about the resident microflora associated with the skin, blood, and gut of healthy captive or wild pinnipeds. The relationship between marine mammals and microflora in their natural environment and changes in such a relationship that may occur when animals are brought into captivity are the subject of an ongoing two year study. Bacteriological cultures were obtained from wild grey seals on their calving grounds in Nova Scotia and, over a period of eight months, from captive specimens maintained in freshwater and in saltwater. This paper presents some initial findings and addresses some questions concerning the microbiology of these aquatic mammals. Preliminary findings suggest that these pinnipeds in their wild environment maintain a very simple microflora; major changes and drifts in the microbial populations have been noted in the captive grey seals. Over 90% of the blood samples collected from the wild seals were positive for bacteria. Changes induced by captivity (e.g., food, water parameters [chlorinated, freshwater vs. saltwater], stress, handling) seem to have a marked effect on the microflora of these animals. It is known that when a very simple or delicate microbial population in humans is altered to any degree, opportunitistic and potential pathogens can gain entrance and produce pathological changes. The potential of this occurring in captive grey seals is discussed.