The marine benthic green algae of the north coast of Papua New Guinea (mainly from Madang province) are documented, based on collections made by the first author between 1980 and 1990. All records (118 taxa) are listed with bibliographic, taxonomic, nomenclatural and biogeographical notes. Identification keys are added for genera represented by at least two species. Representatives of the Pseudocodiaceae and some Udoteaceae are illustrated. The green algal flora of the north coast appears to be much richer than that of the south coast where 72 taxa, including 19 unchecked records from literature, are recorded from the Port Moresby area. ?? 2001 Adac/??ditions scientifiques et m??dicales Elsevier SAS.