The distribution of carbonic anhydrase (CA) in the rabbit eye was studied by light and electron microscopy according to the histochemical method of Hansson. In the cornea, CA staining was found in the cytoplasm of the endothelium. The filtering tissue in the chamber angle did not stain. The pigmented epithelium of the iris and the non-pigmented epithelium of the ciliary body showed intense staining distinctly located at lateral and apical cell membranes, without clearcut regional differences. In the Müller cells of the retina cytoplasmic staining was found. The dilatator muscle of the iris, the pigmented epithelium of the ciliary body, and the pigment epithelium of the retina showed similar and intense staining: cytoplasmic, mitochondrial, and at the cell membranes. The similarity of CA staining in these areas suggests similarity in function, possibly as transport processes important for the nutrition of the overlying cells. However, the role of CA in the various locations remains speculative, except in the corneal endothelium and the prelenticular ciliary processes, where the enzyme is evidently concerned with transport of salt and water.