In the last decade, several survey and research efforts have been undertaken to better understand the ecology and distribution of Harlequin Ducks (Histrionicus histrionicus) in Québec. The results of these efforts are summarized and new survey, research and management needs are identified. Harlequin Ducks breed on rivers and streams of the Gaspé Peninsula, the Québec North Shore, and the immense Hudson Bay and Ungava Bay drainage basins. Québec is possibly the most important breeding area for Harlequin Ducks in eastern Canada, and there is every indication that a significant proportion of the birds wintering in south-western Greenland and in eastern North America breed in Québec. In spring, significant numbers of birds spend a few days or weeks along the Gaspé Peninsula before departing for their breeding or molting areas. The most important molting sites in Québec are Bonaventure Island, the Port-Daniel/Newport area, and the Pointe du Sud-Ouest/Jupiter River area on Anticosti Island. Known fall staging areas include the coastal waters of the Gaspé Peninsula, the Pointe du Sud-Ouest/Jupiter River area, and Brion Island, on the Magdalen Islands. The few Harlequin Ducks that overwinter in Québec are mostly in Baie des Chaleurs, on the south shore of the Gaspé Peninsula. There are no good data on trends of Harlequin Ducks in Québec. Major threats to population recovery/health include hydroelectric developments, illegal and subsistence harvests, coastal exploitation (aquaculture, fisheries, boating), and recreational activities on breeding rivers and streams. Survey, research and management needs include better estimates of breeding densities and distribution, characterization of spring, summer and fall coastal habitats, comprehensive genetic analysis, monitoring, and public education on the status of Harlequin Ducks.