In order to assess the cerebral distribution of intracarotid chemotherapy, 17 postoperative patients with brain tumor underwent brain SPECT obtained by intraarterial infusion of 18.5 MBq of 99mTc-HMPAO. Injection methods were continuous (5.0 ml/min) or pulsatile infusion with supraor infraophthalmic catheterization. The findings obtained by brain SPECT were frequently different from those of angiography and/or DSA. In supraophthalmic catheterization with continuous infusion, only 2 of 10 studies (20%) had homogeneous distribution and 5 of them (50%) had maldistribution of 99mTc-HMPAO which appears in association with laminar flow effect. The remaining 3 studies showed localized distribution (two: tumor localization, one: healthy brain localization). On the other hand, all of 5 studies with pulsatile infusion had homogeneous distribution of 99mTc-HMPAO. In infraophthalmic catheterization, all but one of 5 studies had homogeneous distribution with continuous infusion. These results suggest that pulsatile infusion may be effective in eliminating maldistribution of 99mTc-HMPAO in supraophthalmic catheterization. In conclusion, we are convinced that 99mTc-HMPAO is a useful intraarterial agent for assessing cerebral distribution of intracarotid chemotherapy.