Abstract: In search of agents for tumor prevention, attempt to improve the biological activity of the parent compound, retinoic acid, was carried out by preparing its esters and amides through which the physical and chemical properties and pharmacodynamics might be changed. Twenty-seven retinoic acid esters and retinamides were prepared by treating the corresponding amine and alcohol with retinyl chloride which was obtained from retinoic acid and phosphorous trichloride. Animal tests of part of the compounds reported in this paper showed that some of them exhibited preventive activity against carcinogenic action of nitrososarcosine among which compound (1), N-(4-ethoxycarbophenyl) retinamide showed higher activity and lower toxicity.