Of the antiviral agents currently available to patients with chronic hepatitis B (CHB), entecavir (ETV) and tenofovir disoproxil fumarate (TDF) are 2 of 3 first-line agents.1-3 Given the well-known renal and bone toxicity associated with TDF,4 major international hepatitis B virus treatment guidelines recommend ETV over TDF in patients with predisposing factors to kidney function decline.1-3 However, as evidenced by recent studies, nephrotoxicity of antiviral agents is still an issue under debate.5-7 Therefore, we investigated the differences in the risk of kidney function decline in patients with treatment-naive CHB who were treated with ETV or TDF.