Human ciliary body epithelial cells have been maintained in vitro and have been partially characterized by the determination of growth rate, morphology, and ultrastructural parameters. The dissection technique employed allows the separation of pure ciliary body epithelium with a predominance of cells being from the nonpigmented layer. Growth curves indicate this cell population follows a prolonged rate of growth compared to other primary cell cultures. Loss of pigment granules noted by light microscopy were documented by morphometric analysis of electron micrographs. Thirty-two percent of the cultures attempted were successful. Maintenance of these cells in vitro may provide a means for studying their enzyme systems, growth factors, reactions to various stimuli, and the effects of this cell population on other intraocular tissues.