The marine benthic red algae of Motupore Island and vicinity (Port Moresby area, Papua New Guinea [PNG]) are documented and 36 of the 161 species are illustrated. All records are listed with bibliographic, biogeographic, taxonomic and nomenclatural comments. Apart from several undescribed taxa, which we are in the process of describing separately, none is endemic to the island at this stage. The discovery of the east Australian species Gracilaria rhodymenioides represents a substantial range extension as does Ceramium lentiforme from New South Wales. One species of Gibsmithia also represents a significant range extension from its Lord Howe Island, Norfolk Island and southern Great Barrier Reef distributions. Platoma ardreanum is reported from outside its Hawaiian distribution for the first time, and the Caribbean Renouxia antillana represents a major range extension for the Pacific. Forty-four species appear to be newly recorded for the PNG marine flora and 108 are new records for the Island itself. Because all collections were taken during the month of July, many seasonal entities may be missing from this list and the total marine flora is not yet known. Moreover, because previous records are quite detailed with respect to epiphytic and turf algae, we have not concentrated on these species. The non-geniculate coralline algae have only been collected sporadically as part of this survey.