Detailed littoral and sublittoral survey of fauna and flora of Bardsey Island carried out in order to determine whether Bardsey warrents consideration as a PMNR. Faunal and floral data was recorded as either presence/absence or on a 3 - 4 point abundance scale. The island's shores and sublittoral were very current swept and exposed to wave action, except for limited shelter at Henllwyn. Shore fauna and flora was generally comparable to other exposed shores on west Anglesey. No actual changes in littoral fauna could be discerned from these recorded by Pyefinch (1943). However, the alga Nemalion helminthoides recorded by Jones (1978) was absent at the time of this survey, but this species is known to be of sporadic occurrence in north Wales. Dosya hatchinsiae was found in 1977, but was not recorded in 1955. Sublittoral sampling was carried out using transects, and spot dives, and recording prominent species on an abundance scale. Algal cover was extremely dense as a result of good water clarity. A number of 'southern' species were found. Records currently considered sensitive have been removed from this dataset.