The Xisha Archipelago, South China Sea, was surveyed for waterbirds in March-April 2003 and April-August 2004. Forty-five waterbird species were recorded, making a grand total of 53 species for the Archipelago when earlier published records are included. The Archipelago is of great importance for the Red-footed Booby (Sula sula), with an estimated 10% of the world population breeding on Dong Island. Other breeding seabird species were Great Frigatebird (Fregata minor), Great Crested Tern (Sterna bergii) and Sooty Tern (S. fuscata), and it is believed that Black-naped Tern (S. sumatrana) and Roseate Tern (S. dougallii) also breed there. Compared to 1926, the number of seabirds, and the islands on which they breed, has declined greatly. The data for Ardeidae and shorebirds provide information on migration and, possibly, wintering strategies of these species. Despite habitat degradation and human disturbance, the Xisha Archipelago is still important for breeding seabirds and there is an urgent need to improve the conservation status of this bird group.