Insight into the impact of a pollutant on marine organisms may be gained from four types of biological and chemical investigations: a) short-term acute toxicity tests,b)organism-environment transfer studies,c)physiological studies and d)field studies.In the case of oil pollution,field studies have limited value for the estimation of the impact of oil on natural communities since results are often confused with the effects of "detergents"used in cleanup processes. Both types of laboratory studies(acute toxicity and sublethal toxicity tests)provide valuable information for the toxicity of oils and oil dispersants.Since in the case of oil pollution treatment, oils and detergents are acting in combination,a realistic approach of laboratory studies must also include the combined action of these substances on marine organisms.Although acute toxicity studies which measure the mortality due to a toxicant are very useful for the determination of the range of animal tolerance,other effects causing physiological alterations may be detrimental to a population's survival. This paper concerns research on the effects of an oil,an oil dispersant and of the mixture of oil and dispersant on a physiological process;the respiration of the brine shrimp Artemia salina. MATERIAL AND METHODS Adults of Artemia hatched from commercially available cysts(New Technology Artemia salina Revolution)were used as test animals.The hatching of the cysts and rearing of Artemia was performed in constant temperature rooms at 22+0,5~ in synthetic sea water (Synthetica). The three toxic solutions tested were a crude oil(tunesian crude oil zarzaitine type),anoil dispersant(Finasol-OSR2)and their mixture. The type of oil/water mixture tested was oil-water dispersion(OWD).