Purpose: This study was evaluated the clinical implications of the Tyrosine Hydroxylase (TH) expression in the peripheral blood ( PB), by analyzing correlation of the PB TH with other prognostic factors of neuroblastoma. Methods: Expression of tyrosine hydroxylase mRNA in PB obtained from 178 patients diagnosed with Neuroblastoma was measured by reverse transcriptase-polymerase chain (RT-PCR) and was correlated with other prognostic factors. Result: TH qRT-PCR in the PB was positive in forty-five (19.7%) patients at diagnosis. These patients had a more advanced stage, older age, unfavorable pathology, N-myc amplification, 1p deletion, and accordingly, were a higher risk group. In addition, the probability of 5-year relapse free survival in the TH-positive patients was significantly lower than in the TH-negative patients (54.9%±10.3% versus 93.7%±2.5%, P 0.001). Multivariate analysis revealed the positive TH expression in PB to be an independent unfavorable predictor for RFS (hazard ratio 5.66, 95% confiedence interval 1.79-17.92, P=0.003). Conclusion: TH expression in the PB at diagnosis was associated with high-risk features at diagnosis and a poorer outcome. Therefore, it is necessary to tailor the treatment plan according to the TH expression in PB at diagnosis.