Asphaltene deposition is an ever-increasing problem at Iranian oil reservoirs and in many fields worldwide. Several procedures are used to remove or prevent asphaltene precipitation, but the uses of asphaltene inhibitors provide the most practical and economical solution for treatment of deposits. It is necessary to know the performance of an inhibitor before its application in the field. In this work performance of five inhibitors, namely, benzoic acid, nonylphenol, phenanthrene, phthalic acid, and salicylic acid on three types of Iranian oil with asphaltene content ranging from 0.321, 14.89, and 24.73% have been studied. The optimum concentration of each inhibitor was obtained. The results revealed that salicylic acid has the best efficiency on precipitation reduction for all cases of crudes.