In the rat, unilateral intrastriatal injection of monoclonal antibodies to acetylcholinesterase (AChE) produced ipsilateral disappearance of AChE-positive nerve terminals within striatum and adjacent cortex. No alterations in striatal staining patterns were observed for tyrosine hydroxylase, somatostatin, neuropeptide Y, substance P, or neurotensin. Ultrastructural studies demonstrated the presence of degenerating AChE-positive boutons ipsilaterally, while tyrosine hydroxylase positive terminals seemed unaffected. Apomorphine administration to rats which had received unilateral antibody injection resulted in ipsilateral rotational behavior. These data suggest that selective effects on cholinergic terminals with functional deficits can be produced within the central nervous system by intracerebral injection of AChE antibodies.