The Pain Research Group of the world health organization (WHO) Collaborating Centre for Symptom Evaluation in Cancer Care had developed the Brief Pain Inventory (BPI), a pain assessment tool for use with cancer patients. The BPI measures both the intensity of pain (sensory dimension) and interference of pain in the patients life (reactive dimension). The objective of this review paper was to provide a detailed update of existing evidence on applicability of BPI in evaluation of patients with cancer pain. The BPI demonstrated good construct and concurrent validity. It was translated and validated into many languages - Brazilian, Chinese, Greek, Hindi, Italian, Japanese, Korean, Malay, Norwegian, Polish, Russian, Spanish, Taiwanese and Thai. The BPI was validated in patient populations such as bone metastases, breast cancer and postoperative cancer patients. The BPI can be used both as a quantitative or a qualitative measure for statistical analysis. The BPI was a powerful tool and, having demonstrated both reliability and validity across cultures and languages, was being adopted in many countries for clinical pain assessment, epidemiological studies, and in studies on the effectiveness of pain treatment. Future studies are warranted on its responsiveness and cross-cultural adaptation into other cancer pain syndromes and into other Indian languages.