This chapter examines the preliminary report on adrenal medullary grafting and cografting with sural nerve in the treatment of hemiparkinson monkeys. In the study described in the chapter, 11 juvenile rhesus monkeys (Macaca mulatta) were enrolled. A battery of testing was performed at 3 stages: (1) baseline, (2) post- 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) injection, and (3) post-transplantation. Baseline testing started with a clinical examination of the monkeys to ensure neurological normalcy. Cerebrospinal fluid (CSF) levels of the dopamine metabolite, homovanillic acid (HVA), and the serotonin metabolite, 5-hydroxyindoleacetic acid (5-HIAA), were determined by high performance liquid chromatography with electrochemical detection. Clinical behavior was assessed in a quantitative manner by a two-dimensional computerized movement analysis, indicating the following parameters: the percent of time moving, total distance traversed, and the graphical display of tracking of monkey's movements. The quantitation of drug induced rotation was used to measure the severity of the lesion and as a measure of graft effectiveness. Following the administration of MPTP, all of the animals demonstrated an altered behavior characteristic of parkmsonism. Hypokinesia, bradykinesia, and rigidity of the affected side were quite prominent, while a true tremor at rest was notably absent. The hemiparkinson monkeys demonstrated spontaneous rotation toward the side of the lesion within days following their MPTP injections. In a dose-dependent manner, rotation was accelerated using amphetamine or reversed using apomorphine. © 1990 Academic Press Inc.