The long-term improvement of intrastriatal co-grafts with genetically engineered fibroblasts expressing tyrosine hydroxylase (TH) and glial cell line-derived neurotrophic factor (GDNF) was investigated in the present study. Two recombinant vectors, pCMV-TH and pCI-neo-GDNF, were transfected respectively into the primary fibroblasts, and their expression was further identified by in situ hybridization and immunocytochemistry. The engineered fibroblasts expressing TH, GDNF, or both were transplanted into the striatum of parkinsonian rats, and the therapeutic effects were observed for 20 weeks. Data revealed that only animals with fibroblasts expressing both TH and GDNF exhibited a stable and significant behavioral and biochemical recovery. Moreover, persistence of both TH and GDNF expression in grafts was demonstrated 20 weeks after transplantation. These results suggest that combined transplantation of fibroblasts expressing TH and GDNF can lead to long-term and remarkable therapeutic effects on parkinsonian rat model.