A Drosophila cDNA encoding a structural homolog of mammalian FKBP59 (also identified as FKBP52), a member of the FK506-binding protein (FKBP) class of immunophilins, was isolated. The gene dFKBP59 corresponding to this cDNA has been characterized and mapped to the 30D3-4 region. The predicted amino acid sequence of this cDNA shows that the dFKBP59 protein contains one highly conserved FKBP12-like domain followed by two others with less conservation. Northern hybridization reveals that the dFKBP59 mRNA is expressed throughout the Drosophila life-cycle. In contrast to its mammalian homologs, in situ hybridization detected dFKBP59 expression in specific tissues: the lymph glands, Garland cells and oenocyte cells, which are all specialized tissues in which intensive exocytic/endocytic cycling takes place. Garland cells and oenocytes (also called Drosophila nephrocytes) function in taking up waste material from the hemolymph. Finally, I have mapped an enhancer trap element within the 5' region of dFKBP59 which may help in future studies to address the question of its function during Drosophila development.