This work presents the long-term evolution (12-27 months) of the patients with adrenomedullary autotransplants to the caudate nucleus for the treatment of Parkinson's disease. Sixteen men and 6 women, mean age of 49.9 years, received brain implants of their own adrenal medulla using the procedure of Madrazo et al. (1). Nineteen of the transplanted patients suffered idiopathic Parkinson's disease and 3 of them parkinsonism. Before surgery 20 patients were on L-dopa and suffered collateral signs due to the drug. The degree of severity of their disease was evaluated pre and postoperatively, with and without medication, in their "on" and "off" periods, using the international scales of Schwab and England, Hoehn and Yahr, Madrazo, and the UPRS, and was documented by videotape. Biochemical analyses were made of lumbar and ventricular cerebrospinal fluid, and neuropsychological and neurophysiological evaluations were performed before and after surgery. In some patients, the location and viability of the adrenal medullary implants were demonstrated by brain scintigraphy using 131-I-metaiodobenzylguanidine, a chromaffin specific radiopharmaceutical. The clinical evaluations of 18 autotransplanted patients (4 died) showed their significant functional recovery both in their "on" and "off" periods, that for the first patients operated has remained stable for 27 months. Also, their response to L-dopa improved allowing the reduction of their postoperative doses of medication to 30% of their preoperative requirements, with the disappearance of the collateral effects of the drug.