Surveys of Laysan Albatross and Wedge-tailed Shearwaters on Midway and Oahu Island, Hawaii, identified a high proportion of birds with plastic in the upper gastrointestinal tract, representing hazards to the health of adult birds and their chicks. Fifty Laysan Albatross chicks were examined for plastic items lodged within the upper digestive tract. Forty-five (90%) contained plastic, including 3 chicks having proventricular impactions or ulcerative lesions. Plastic items in 21 live albatross chicks weighed a mean of 35.7 g chicka??1 (range 1a??175 g). Four dead birds contained 14a??175 g (mean 76.7 g). Two of four adult albatross examined contained plastic in the gut. Laysan albatross chicks have the highest reported incidence and amount of ingested plastic of any seabird species. Twelve of 20 adult Wedge-tailed Shearwaters (60%) contained plastic particles 2a??4 mm in diameter. Impaction did not appear to be a significant hazard for adult shearwaters. Shearwater chicks were not examined. Chemical toxicity of plastic polymers, plasticizers and antioxidant additives is low, although many pigments are toxic and plastics may serve as vehicles for the adsorption of organochlorine pollutants from sea water, and the toxicity of plastics is unlikely to pose significant hazard compared to obstruction and impaction of the gut.