Although the concept of cell-based therapy for Parkinson's disease has been around for more than three decades with proof-of-concept studies in man having been achieved, it still remains a controversial experimental therapy. In this review, we discuss the reasons for this and the challenges that this approach generates in the treatment of Parkinson's disease in terms of adopting better strategies by which to develop this whole therapeutic area, an approach that is becoming more necessary as the era of stem cell therapies start to become a clinical reality.