['Increasing evidences have been obtained that immune activation and inflammation play critical roles in the pathogenesis of chronic heart failure (CHF). T helper (Th) 17 cells are a newly found pro-inflammatory T cell subtype. We therefore assessed the hypothesis that circulating Th17 cells increased in patients with CHF. Hypothesis. Th17 cells and its cytokine might be elevated in patients with CHF.', 'A total of 92 patients with CHF and 59 healthy donors were enrolled in the study. The frequencies of circulating Th17 cells were determined by flow cytometry. The interleukin (IL)-17 protein levels in the serum and supernatant of phytohemagglutinin (PHA)-stimulated periphery blood mononuclear cells (PBMCs) were detected using ELISA and the mRNA expression of retinoic acid-related orphan receptor (ROR)γt, which is the key transcription factor of Th17 cells was measured by RT-PCR.', 'There were no significant differences in the frequency of circulating Th17 cells, serum level of IL-17, and expression of RORγt in PBMCs between CHF patients and healthy controls. IL-17 protein level in the supernatants of PHA-stimulated PBMCs was also comparable between CHF patients and health donors.'] Are circulating Th17 cells elevated in patients with chronic heart failure?