Development of an accurate non-invasive imaging technique to detect recurrent and metastatic prostate cancer is critical for the effective management of these patients. The purpose of our study was to determine the diagnostic utility of positron emission tomography with [F-18]fluorodeoxyglucose (FDG PET) in patients with suspected or known metastatic and recurrent prostate cancer. We performed 12 FDG PET scans in 12 men (age 65-81 years) with history of prostate cancer who had previously undergone radical prostatectomy (n=3) or prostate radiotherapy (n=9). Serum prostate specific antigen (PSA) level was elevated in all patients (5-206 ng/ml). Available correlative imaging studies included contrast-enhanced chest, abdomen and pelvis CT (n=8), bone scintigraphy (n=5), and radiography (n=2). PET findings were compared to the findings of the other imaging studies on a lesion-by-lesion basis in individual patients. Validation was by clinical or imaging follow-up for up to 1 year. PET findings were concordant with the findings of the other imaging studies in 7 patients. PET was discordant with the other imaging studies in 5 patients. PET demonstrated suspicious hypermetabolic pelvic lymph nodes in one patient with negative pelvis CT. PET underestimated the extent of osseous metastatic disease in the remaining 4 patients. FDG PET is limited in the detection of osseous metastatic lesions but may be useful in the detection of metastatic nodal and soft tissue disease.