We study the impact of China’s 2013 implementation of Basel III on bank risk-taking and its responses to monetary policy shocks using confidential loan-level data from a large Chinese bank. Guided by theory, we use a difference-in-difference identification, exploiting cross-sectional differences in lending behaviors between high-risk and low-risk bank branches before and after the new regulations. We find that, through a risk-weighting channel, changes in regulations significantly reduced bank risk-taking, both on average and conditional on monetary policy easing. However, banks reduce risk-taking by increasing lending to ostensibly low-risk state-owned enterprises (SOEs) under government guarantees, despite their low average productivity.