Freshly dissected chick neural retina and pigmented epithelium do not apparently contain asymmetric molecular forms (A-forms) of acetylcholinesterase (AChE). The neighboring choroid, and the ciliary muscles and iris, are however rich in type II A-forms (high salt/EDTA-extractable). Most if not all the asymmetric AChE activity detected in chick 'whole retina' preparations could then be explained in terms of contamination by non-retinal eye tissues.