Coimplants of adrenal medulla (AM) and peripheral nerve (PN) in animal models of Parkinson's disease (PD) have shown that AM cells survive longer, tend to show neuronal phenotype, and enhance sprouting of host fibers. Since 1987, our implants of perfused AM and fetal ventral mesencephalon (FVM) in PD patients have achieved varying degrees of clinical improvement. If the donor tissue determines the improvement, different types of implants should result in qualitatively and quantitatively different degrees of improvement. The purpose of this study is to determine whether or not the clinical course, improvement slope, and reduction of medication observed in PD patients who undergo tissue transplantation (Tx) depend on the donor tissue type. In a pilot study, four grade IV-V PD patients received implants of precoincubated autologous AM and intercostal nerve in the caudate nucleus (open surgery). Clinical assessment was based on international scales (UPD) as reported for Tx of FVM and perfused AM. There were no systemic or neurologic complications. Four years post-Tx, longer On phases and improved PD symptoms (ADL and motor-UPD) in On and Off persist in four cases, with reduced dyskinesias. Progress appears to be stepwise, starting within weeks of Tx (similar to AM and sooner than our FVM implants), followed by a period of stability and, after a second wave of improvement 12-18 months post-Tx (similar to FVM implants), continues to date. L-dopa medication has been reduced by more than 60% and dopamine agonist use has not resumed. We conclude that our recipients continue to be clinically better than prior to Tx. The course of recovery after co-Tx of AM and PN differs from that of FVM or AM implants. This fact may be related to the etiological factors that produce the improvement.