biostudies-literatureUnknown5(2)Pan JA growing body of research on large language models (LLMs) has identified various biases, primarily in contexts where biases reflect societal patterns. This article focuses on a different source of bias in LLMs-government censorship. By comparing foundation models developed in China and those from outside China, we find substantially higher rates of refusal to respond, shorter responses, and inaccurate responses to a battery of 145 political questions in China-originating models. These disparities diminish for less-sensitive prompts, showing that technological and market differences cannot fully explain this divergence. While all models exhibit higher refusal to respond rates with Chinese-language prompts than English ones, language differences are less pronounced than disparities between PNAS nexuspgag013https://www.ebi.ac.uk/biostudies/studies/S-EPMC12910507biostudies-literaturePolitical censorship in large language models originating from China.PMC12910507Pan JXu XfalsePolitical censorship in large language models originating from China.A growing body of research on large language models (LLMs) has identified various biases, primarily in contexts where biases reflect societal patterns. This article focuses on a different source of bias in LLMs-government censorship. By comparing foundation models developed in China and those from outside China, we find substantially higher rates of refusal to respond, shorter responses, and inaccurate responses to a battery of 145 political questions in China-originating models. These disparities diminish for less-sensitive prompts, showing that technological and market differences cannot fully explain this divergence. While all models exhibit higher refusal to respond rates with Chinese-language prompts than English ones, language differences are less pronounced than disparities between 2026-01-01T00:00:00Z2026 Feb2026-07-16T07:49:26.071Z2026-07-09T10:46:21.341ZS-EPMC129105074170987410.1093/pnasnexus/pgag013