Abstract: Some tropical agro-forestry systems contribute to the maintenance of diverse vascular epiphytes. Due to high bromeliad density, they may resemble native Brazilian Atlantic forest canopies offering resources for organisms living at the top of the trees such as ants. The present study investigates the importance of epiphytes on trees planted to shade cocoa plantations as habitats for ants. The following hypotheses were tested: (I) The bromeliad structure and location (distance from the tree centre) in the canopy affect ant species richness; (II) epiphytes with suspended soil support higher ant species richness; (III) the composition of ant assemblages differs between bromeliads with and without suspended soil and also as a function of bromeliad size; (IV) epiphyte-dwelling ant species composition depend on the epiphyte genera and species. The study was carried out in March 2007, in a cocoa agro-forestry area froms the Cocoa Research Center, Ilhéus, state of Bahia, Brazil. On a single Erythrina tree, 47 ant species were collected in 36 out of the 52 bromeliad epiphytes sampled. The ant composition was strongly affected by the presence of suspended soils where many bromeliads root. We detected a significant negative correlation between location of the bromeliad and ant richness. The ant species richness and composition depended on the epiphyte size and the occurrence of suspended soil. These results stress the importance for biodiversity conservation in agroforestry systems of choosing shade trees that can accommodate epiphytes. This study demonstrates the remarkable diversity of ants associated with the epiphyte community of a single tree, in addition to the distinctive association between the different species of epiphytes, their physical characteristics, and their inhabiting ant fauna.