Sixteen beluga whales (Delphinapterus leucas) and fifteen ringed seals (Phoca hispida) from the western arctic region of Canada were examined for giardiasis and cryptosporidiosis. Intestinal contents from the rectum and colon were collected from animals slaughtered by Inuit hunters. A fluorescent monoclonal antibody identified Giardia sp. cysts in three of 15 (20%) seals. Thus, ringed seals are implicated as a potential reservoir for this zoonosis in the arctic.