Tseng CW, et al. - As the pathogenesis and disease progression of chronic viral hepatitis are affected by regulatory T cells (Tregs), researchers here examined the frequency and function of Tregs in cases with chronic HBV/HCV co‐infection. They divided 74 untreated HBV/HCV co‐infected patients into four subgroups: HBV‐active/HCV‐active (BACA), HBV‐inactive/HCV‐active (BICA), HBV‐active/HCV‐inactive (BACI), and HBV‐inactive/HCV‐inactive (BICI). The fraction of CD4+Foxp3+T cells among CD4+T cells was determined for calculating Treg frequency. There were 8 patients of BACA (10.8%), 38 of BICA (51.4%), 14 of BACI (18.9%), and 14 of BICI (18.9%) among the 74 patients. The four groups were comparable regarding the frequency of CD4+Foxp3+T cells. Observations revealed that HBV/HCV co‐infected patients with active HCV infection exhibit higher inhibitory function of Tregs. A dominant role ALT abnormality is suggested in Treg function.