The IPSAQ is a self-administered instrument designed to evaluate individuals' attributional style (AS). The purpose of this study is to examine the psychometric properties of the Chinese version of the Internal, Personal and Situational Attributions Questionnaire (C-IPSAQ). We also investigate if patients with depression and patients with delusions exhibit attributional biases. The English version of IPSAQ was translated into Chinese and back-translated into English for use in this study. 200 normal control individuals, 47 depressed patients, and 41 delusional patients diagnosed with schizophrenia were recruited for this study. Psychometric properties of this questionnaire were evaluated. The IPSAQ was found to have good internal consistency as a scale. The mean Cronbach's alpha of the six subscales was 0.697. The inter-rater reliability was also acceptable. The concurrent validity analysis revealed that the C-IPSAQ was significantly correlated with ASQ. The group-comparison analyses showed differences in attributional style between patients with depression and patients with delusions compared to normal controls. We confirmed the reliability and validity of the C-IPSAQ, and that the instrument can discriminate specific attributional biases between different patient populations. The C-IPSAQ is a valid instrument to assess attributional style in delusional and depressed patients.