Biological surveys of seven rocky shores along Yorkshire's coastline were carried out in the spring and summer of 1991. Most of the shores had conservation value and were designated under the various categories Heritage Coast, SSSI and North York Moors National Park. Public access to all the sites was relatively easy. The topography of the shores was varied, although the presence of a wave cut platform was a fairly consistent feature. A large number of species were recorded during the surveys, including some which are considered to be rare or of a south western distribution. However the biological communities were fairly homogenous throughout the sites, differing largely in the extent and degree of algal cover and the density of Littorina littorea populations. The species richness of the sites appeared to correlate well with the complexity of the shore, wave exposure and turbidity. Some of the sites appeared to be mildly affected by raw sewage discharges, but none were as degraded as the rocky shores between Scalby Ness and Jackson's Bay since the construction of the Scarborough's short sea outfalls.