RI-angiography with 99mTc microsphere albumin (MISA) was performed to evaluate the distribution during intra-arterial infusion chemotherapy from October 1985 to November 1987 at Tokyo Women's Medical College. Thirty studies were carried out in twenty-one patients with oropharyngeal (11), oral cavity (6), maxillary sinus (3) and laryngeal cancer (1). Six mCi of 99mTc-MISA was slowly injected through the intra-arterial catheter in 1-2 minutes. The evaluation of RI-distribution was classified into the following three categories: Excellent, all of the tumor are covered; Good, more than 50% of the tumor; Poor, less than 50% of the tumor. Good or excellent distribution was obtained in 18 of 21 cases (86%). Sequential perfusion studies were performed on 8 cases. Three cases had evidenced excellent or good distribution during the treatment. Five cases showed poor distribution in the first study. In three of these cases, distributions were improved after replacement of the catheter, RI-distribution at the internal carotid arterial area was seen in three patients, and in two of them, excellent or good distribution was obtained after replacement of the catheter. These data suggested that RI angiography with 99mTc-MISA was useful for evaluation of the drug distribution during intra-arterial infusion chemotherapy, especially for detection of abnormal distribution in the internal carotid arterial area.