The phytal fauna ofUlva fasciata off Visakhapatnam coast were investigated during the period January, 1967 to December, 1968. The standing crop of the alga ranged between 900 g and 1575 g/m² of rock surface. The maximum growth was observed during July–August in both the years and the minimum in April. The total non-sessile faunal density ranged from 413 to 10166/100 g of alga with the maximum numbers in April–May period and the minimum in January, 1967 and July, 1968. The maximum faunal density occurred when the algal thalli were declining and degenerating and the ambient hydrographical conditions (like salinity and temperature) were steady. Gastropods, bivalves, isopods, amphipods and decapods were abundant when the alga was prolific and while withering, foraminiferans, nematodes, polychaetes, halacarids, chironomids and copepods were high in numbers. The phytal faunal density of the present area compares favourably with those from temperate belt. The primary importance of the algal structure, which determines the degree of sedimentation, the animal composition and the relative abundances of the faunales is discussed.