The existing means of detecting recurrent ovarian carcinoma are notoriously poor. Positron emission tomography (PET) is a form of computer-assisted imaging which produces images reflective of the biochemistry of the tissues rather than their physical characteristics. PET imaging with the positron emitting glucose analog 2-[18F]-fluoro-2-deoxy-D-glucose (FDG) exploits the accelerated rate of glycolysis characteristic of malignant tissue to image tumors. To begin to study PET's ability to diagnose recurrent ovarian cancer, whole-body PET FDG scanning was performed on 13 patients prior to planned surgical exploration. Seven patients were suspected of having recurrence based upon clinical findings, and 6 patients were clinically free of disease. In all 6 of the patients with suspected recurrence who subsequently underwent surgery, PET images demonstrated increased FDG uptake in a distribution that correlated with surgical-pathologic findings. Both intraperitoneal and extraperitoneal lesions were detected by PET. All 6 patients judged clinically free of disease had negative PET scans, but in 5 of these microscopic foci of residual tumor were found at surgery. Although PET FDG cannot replace surgery in the detection of microscopic recurrence, it can accurately detect tumors greater than 1.0 cm in diameter.