A chemical agent contained in the rat pup preputial gland was found to regulate anogenital licking, a behavioral pattern crucial to pup survival. Combined gas chromatography and mass spectrometric analysis led to identification of four components in addition to high molecular alkanes (waxes). Independent synthesis added to behavioral observations were used to quantify the dam's response to these components. Among them, dodecyl propionate (DP), a pheromone-like compound, appears to be the only one efficient enough to induce, in the dam, behavior patterns similar to those observed with crude lipidic extract from the preputial gland secretion. Various esters previously were predicted in the adult rat preputial gland. DP is the first ester identified from mammalian infant tissue. These results, in combination with previous findings, allow discussion of the DP pheromonal role.