A catalogue of the benthic algae of the Ria de A Coruna (NW Iberian Peninsula) is presented. In all, 339 specific and infraspecific taxa were identified, including 26 Cyanophyta, 193 Rhodophyta, 71 Phaeophyta, 2 Xanthophyta, and 47 Chlorophyta. For each specific and infraspecific taxon, we report littoral level, wave exposure, substratum and seasons of collecting. Many taxa are of biogeographical interest. Some have recently been recorded for the first time from the Iberian Peninsula or at least Galicia. In this paper, the following are newly recorded from the Iberian Peninsula: Gelidioxolax margaritoides, Heterosiphonica crispella var. laxa, Lomentaria hakodatensis and Vaucheria erythrospora. In addition the following are newly recorded from Galicia: Codiolum petrocelidis stadium, Desmarestia dresnayi, Entocladia tenuis, Microcoleus wuitneri, Phyllophora sicula, Pterosiphonia ardreana, Solieria chordalis and Ulva scandinavica. We propose the names Colaconema caespitosum (J. Agardh) comb. nov. and Chondracanthus teedii var. lustitanicus (Mesquita Rodrigues) comb. nov. The number of specific and infraspecific taxa in the Ria de A Coruna is high relative to the small size of the area. This species richness is a consequence of the diversity of habitats found in such topographically complex estuaries ('rias'). About 45% of the species recorded for the warm-temperate NE Atlantic Ocean were found in the surveyed area.