We report Musonycteris harrisoni (Phyllostomidae) and Tlacuatzin canescens (Didelphidae) feeding of flowers during the blooming period (March and April 2004) of Stenocereus queretaroensis, an endemic cactus showing nocturnal anthesis and chiropterophilic syndrome. Visits were considered legitimate because both mammals made contact with the stigma and anthers, although their visits were highly infrequent compared with the principal pollinator Leptonycteris curasoae. These mammals are usually associated with pristine tropical forests, although our study site showed high habitat fragmentation and extensive agriculture. It is likely that both mammals feed regularly on nectar of cacti in pristine tropical forests thus acting actively as pollinators. © 2007 Academic Journals Inc.