CT-aided fine needle biopsy was performed in 48 patients with pelvic space-occupying lesions demonstrated by computer tomography. Amongst 36 patients with malignant neoplasms, recurrences or metastases, malignant cells were found in 26 (72%). In six out of twelve patients suspected of having a pelvic abscess, fine needle puncture confirmed the diagnosis by providing positive bacteriological results. CT-aided puncture should be used in conjunction with computer tomography in order to clarify the aetiology of space-occupying lesions. The indication for CT-aided puncture is the presence of a pelvic space-occupying lesions which cannot be demarcated by sonography.