Coastal areas of Rio Grande do Sul serves as a feeding place for many seabirds which occasionally end up victimized of human activities at sea. Aiming to evaluate the effects of fishery and crude oil contamination and ingestion of synthetic materials on seabirds, monthly monitoring visits were done from July 1998 to July 1999 in order to count dead birds found on the shore of Rio Grande do Sul. A total of 7690 carcasses of 18 seabird species were found; 81% were Magellanic Penguins (Spheniscus magellanicus) and 19% were Procellariiformes. Diomedeidae and Procellariidae counted for 7.5% and 92.5% of Procellariiformes, respectively. A total of 4003 (52%) carcasses were in condition allowing proper evaluation of causes of death, which were indeed verified in 1319 (33%) carcasses. Among the most clearly visible signs, 812 (61, 5%) had crude oil stains on their feathers and 507 (38, 5%) had cuts of sharp objects or marks of fishing nets. Besides that, 581 stomachs were extracted from which 339 (58%) showed signs of ingestion of synthetic materials. Accepted 7 October 2001.