We determined the breeding systems, in this case the physiological acceptance or rejection of self-produced pollen, of epiphytic species in a tropical montane wet forest in Monteverde, Costa Rica. Controlled pollinations were performed in the field and self-compatibility was determined on the basis of fruit set. All fifteen species, distributed among five families, were found to be self-compatible. This represents the highest incidence of self-compatibility among any life form at any tropical site. It is suggested that aspects of epiphytic existence may favor self-compatibility. Thus, some inbreeding may occur in the epiphytic community, despite the prevalence of highly specialized pollination systems which promote outcrossing.