Although fringing -ree.fs abound in the coastal waters of western, south-western and southern coasts of -Sr.i Lanka, only a few areas contain true,-coral reefsThe major part of the reefs of .these areas contain,sandstone and granite .reefs. -The ’sandstone’ reef s are the dominant type-and in many instances-contain a su perficial veneer of hermat-ypic^cjprais. Inspite of the coral-coyer being ratji.gr. low with a percentage cover of usually less tha’rk 10%, their diversity was rela tively high as compared to true coral reef areas. The granite reefs were much more poorer in terms of both percentage coral cover as w ell as d iversity. Reef surveys conducted on 50 sites:from KandaRuliya in the northern part of thc-west coast tpr'Tangalle in the south-coast of S r i’Lanka gave‘ a yield of 15 genera and 64 species of stony corals which had not been previously recorded for Sri Lanka. One possibly new hermatypic genus collected during the survey is under investigation by the Australian Institute of Marine Science. The status of the reefs investigated including potential threats and the ecology of the new stony corals recorded for Sri Lanka are discussed. The problems encountered in the preparation of an updated checklist of stony corals for Sri Lanka due to the need to eliminate synonymous taxa and errors in previous records are also discussed.