One hundred eleven patients with advanced cancer and pain newly referred to a palliative care center completed the Brief Pain Inventory (BPI) weekly for up to 4 weeks. The aims were (a) to review the numbers and causes of pain, (b) to consider the usefulness of the BPI in the evaluation of pain in cancer patients, and (c) to determine the impact of treatment. A total of 370 pains were recorded initially, a median of 3 per patient; 85% had more than 1 pain and more than 40% had 4 or more pains. Causes of pain were cancer (46%), debility (29%), treatment (5%), concurrent disorder (8%), and no stated cause (12%). The top 10 individual causes accounted for 73% of the pains. Seventy-six (68%) of the patients completed two BRIs, but only 46 (41%) completed 5. After 4 weeks, the median number of pains had fallen to 1.5; 78% still had more than 1 pain, but only 20% had 4 or more pains. Intensity of pain also declined, particularly in the first 2 weeks. With their last BPI, 23% had become completely pain free and a further 27% achieved acceptable relief (worst pain scores 1-4), compared with none and 24% initially. Of those who completed all five BPIs, the final respective figures were 22% and 29%. In contrast, 23% of patients still had unacceptable severe pain noted on their last BPI (worst pain scores 8-10), compared with 36% initially. Of those who completed five BPIs, the final figure was 20%. Highly significant correlations were observed between all seven interference factors and present, worst, and average pain intensities. After 4 weeks, the pattern was more variable, particularly in relation to present pain, suggesting that interference factors may have a limited utility as a measure of satisfactory pain management. Many patients did not answer all the questions in the BPI. It was concluded that the BPI is not brief enough for routine clinical use, and that the short form of the BPI (BPI-SF) is too short. A pain diary card will be developed comprising mainly pain scores, a pain relief score and a satisfaction with pain management score.