Assessment of pain in cancer patients is very important to all health care professionals. This paper describes the development of a Taiwanese version of the Brief Pain Inventory (BPI-T) and discusses its psychometric properties in Taiwan. The BPI-T was developed from the original BPI using back-translation and committee review. A total of 534 cytologically or pathologically diagnosed cancer patients in three medical centers in Taiwan were interviewed between July 1992 and October 1997. The intraclass correlation coefficient for the test-retest reliability was 0.79 for the pain severity scale and 0.81 for the pain interference scale. The explained variance for the within-scale factor analyses was larger than 60% in both scales. The coefficient alpha for the internal reliability was 0.81 for the severity scale and 0.89 for the interference scale. Confirmatory factor analysis of the BPI-T clearly identified the same two scales (severity and interference scales) in the 299 adult patients (age between 20-64) with high education (education years > 9) or patients at an early stage of disease. However, in the 235 nonadult patients with distant metastasis or low education patients with distant metastasis, the "most severe pain" item loaded more to the interference scale than the severity scale. Convergent validity of the pain severity was demonstrated by significant correlations with stage of disease (National Cancer Institute's Surveillance, Epidemiology, and End Results Program [SEER]), performance status (Eastern Cooperative Oncology Group [ECOG]), and pain interference. In conclusion, interviewer-administered BPI-T was a reliable instrument for cancer pain severity and its interference in Taiwan. Additionally, it was a valid instrument on adult cancer patients with high education or patients at an early stage of disease.