Purpose: We evaluated positron emission tomography (PET) with 18fluorine fluorocholine (18F FCH) for the pretreatment localization of prostate cancer. Materials and Methods: A total of 17 patients with prostate cancer who had not yet received treatment for the disease underwent whole body PET following intravenous administration of 3.3 to 4 MBq/kg 18F FCH. PET findings were compared with the results of prostate sextant biopsy and other imaging studies, and the clinical course. Tracer uptake in prostate sextants was measured as a maximum standardized uptake value (SUVmax) and evaluated as a predictor of the prostate sextant biopsy result by ROC analysis. Results: Prostate sextants positive for malignancy on biopsy demonstrated significantly higher SUVmax than biopsy negative sextants (mean 5.5 vs 3.3, p 18F FCH uptake. PET with 18F FCH is potentially useful for staging and localizing prostate cancer.