Tseng CW, et al. - Researchers examined the frequency and function of regulatory T cells (Tregs) in cases with chronic hepatitis B virus (HBV)/hepatitis C virus (HCV) coinfection. Enrollment of untreated HBV/HCV co‐infected patients was done. The fraction of CD4+Foxp3+T cells among CD4+T cells was determined to calculate Treg frequency. Percent of inhibition of T‐cell proliferation defined Treg‐mediated inhibition. Among 74 enrolled patients, 8 cases (10.8%) were HBV‐active/HCV‐active, 38 cases (51.4%) were HBV‐inactive/HCV‐active, 14 were HBV‐active/HCV‐inactive (18.9%) and 14 were HBV‐inactive/HCV‐inactive (18.9%). The four groups were comparable in terms of frequency of CD4+Foxp3+T cells. Outcomes revealed higher inhibitory function of Tregs among the HBV/HCV co‐infected patients with active HCV infection. They suggested a dominant role of alanine aminotransferase abnormality in Treg function.