Parkinson's disease is a degenerative neurologic disorder that currently affects half a million Americans. There is no known medical treatment that stops or reverses the dopaminergic neuronal degeneration that causes the symptoms. Investigators are searching for new surgical treatments that may provide better control of symptoms for longer periods of time. Reinnervating the basal ganglia with dopaminergic neurons is the theory behind fetal neural tissue transplantation. A review of the clinical trials of fetal neural tissue transplants performed in Mexico, Sweden, England and the United States shows some improvement in motor function in patients with severe idiopathic Parkinson's disease. Comparing the results of the different clinical trials is difficult due to a number of varying factors between the groups. There is still no consensus regarding patient selection, optimal fetal tissue source, optimal site of implantation, the use of immunosuppression or optimal method of assessing patient response. Much research is still required before fetal neural tissue transplantation can be offered as a therapeutic option for patients with Parkinson's disease.