Oil exploration and development with the threat of pollution to living marine resources has increasingly become a public issue.The shift in balance of an ecosystem from a severely altered one, immediately following a major oil spill to a stable ecosystem can require many years. Certain organisms can be killed by water-soluble fractions (WSFs) of oil and exhibit sublethal response at much lower concentrations (1 to 10 ppb). The carcinogenic properties and anthropogenic origins of polyaromatic hydrocarbons in the crude oil have led to interest in understanding their distribution and fate in the environment. The aim of researcher is to study and evaluate the toxic effects of water soluble fractions (WSFs) of Persian Gulf and Bombay High Crude oil on common marine clams of Mumbai coast such as Gafrarium divaricatum and Dosinia fibula, so as to serve as a baseline for monitoring the consequences of petroleum toxicity. Clams are widely distributed and are of great value as food for man. Because of increased demand and decreased production due to water pollution and other causes, their market price has increased greatly during past few years.