Due to the low prevalence of hemangiopericytomas (HPCs), data on the biophysiological characteristics of this tumor are rare. Positron emission tomography (PET) demonstrated a sixfold increased uptake of [C-11]methionine and hyperperfusion in the HPC, whereas glucose utilization was decreased in this area. This low glucose utilization is in contrast to the high [C-11]methionine uptake and the malignancy of these tumors. The characteristics of HPCs in PET described herein for the first time offer additional diagnostic criteria and may help especially to differentiate these tumors from meningiomas.