Neuroblastoma (NB), originating from neural crest cells, is the most common extracranial tumor of childhood. Retinoic acid (RA) which is the biological active form of vitamin A regulates differentiation of NB cells, and RA derivatives have been used for NB treatment. PPAR alpha (peroxisome proliferator-activated receptor) plays an important role in the oxidation of fatty acids, carcinogenesis, and differentiation. URG4/URGCP gene is a proto-oncogene and that overexpression of URG4/URGCP is associated with metastasis and tumor recurrence in osteosarcoma. It has been known that URG4/URGCP gene is an overexpressed gene in hepatocellular carcinoma and gastric cancers. This study aims to detect gene expression patterns of PPAR alpha and URG4/URGCP genes in SH-SY5Y NB cell line after RA treatment. Expressions levels of PPAR alpha and URG4/URGCP genes were analyzed after RA treatment for reducing differentiation in SH-SY5Y NB cell line. To induce differentiation, the cells were treated with 10 mu M RA in the dark for 3-10 days. Gene expression of URG4/URGCP and PPAR alpha genes were presented as the yield of polymerase chain reaction (PCR) products from target genes compared with the yield of PCR products from the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene. SH-SY5Y cells possess small processes in an undifferentiated state, and after treatment with RA, the cells developed long neurites, resembling a neuronal phenotype. PPAR alpha gene expression increased in RA-treated groups; URG4/URGCP gene expression decreased in SH-SY5Y cells after RA treatment compared with that in the control cells. NB cell differentiation might associate with PPAR alpha and URG4/URGCP gene expression profile after RA treatment.