The snow petrel Pagodroma nivea is an obligate associate of sea-ice and one of the most abundant seabird species of the Southern Ocean. Time- and sex-specific annual variation in adult survival was estimated using capture-mark-recapture of petrels nesting at Pétrels Island, Terre Adélie, 1981-1997. On the basis of a regression analysis, 44% of the variation was linked inversely to the latitudinal extent of sea-ice during winter (June) in the region offshore of the study colony, where this population is likely to spend the non-breeding season. Monthly sea-surface temperature anomalies tended to influence adult survival but the relationship was not statistically significant. Why sea-ice extent should have such a critical effect on this species is yet to be explained, but the relationship, in the context of environmental warming and the consequent potential loss of Antarctic sea-ice, is an important one for this species.