BACKGROUND/PURPOSE: It has been shown that the abnormality in immune cells in chronic fatigue syndrome (CFS) patients is closely associated with the participation of TGF-?. In order to study the relationship between TGF-?1 and CFS, we investigated the mRNA levels of TGF-?1 in peripheral blood mononuclear cells (PBMCs) in patients with CFS. METHODS: Fluorescent quantitative real time reverse-transcription polymerase chain reaction (FQ-RT-PCR) was performed to test TGF-?1 mRNA expression in PBMCs in 63 cases of CFS, 50 cases of disease controls, and 50 cases of healthy controls. RESULTS: The mean value of TGF-?1 mRNA expression in CFS patients was ??Ct=1.17±0.58, which was significantly higher than the disease controls (??Ct=0.07±1.08, df=111, p < 0.01) and the healthy controls (??Ct=0.00±1.63, df=111, p 0.05). CONCLUSION: The expression of TGF-?1 in PBMCs is significantly elevated in patients with CFS. It might be correlated to the pathogenesis of the disease. Copyright © 2011. Published by Elsevier B.V.