Single photon emission tomography (SPET) employing 99Tcm-sestamibi (MIBI) injected intravenously was performed in 27 patients for pre-surgical evaluation of intraparenchymal brain tumours. A computerized tomography (CT) scan was performed in 26 patients, magnetic resonance imaging (MRI) in 8 patients and digital subtraction angiography (DSA) in 14 patients. Visual analysis of the SPET scans was performed using a 4-point scale relating to background activity, to evaluate MIBI uptake in the tumour. The vascular supply and the cellular component were also evaluated using DSA and CT scans. In normal controls, MIBI uptake was observed in the scalp, in the choroid plexus and in the pituitary gland, but never in normal parenchyma. Among the astrocytoma group of patients, a trend between MIBI uptake and grade of tumour was noted. MIBI uptake in meningiomas depends primarily on the vascular supply. Our results support the hypothesis that vascular supply, integrity of the blood-brain barrier, the degree of malignancy of the neoplasm and the viability of the tumour cells may be related to MIBI uptake.