Intra-abdominal abscess, resulting either from primary intraperitoneal disease or as a complication of surgery, remains a serious problem with high patient mortality if not treated early and adequately. The initial attempt at diagnosis rests on strong clinical evidence supported by nonspecific laboratory findings. The most helpful advance over conventional x-ray studies has been the advent of noninvasive imaging techniques such as ultrasonography or computed tomography. Radioisotopic scanning with gallium or indium makes possible a generalized survey of the peritoneal cavity, but only after a delay from the time of injection. Ultrasonography is somewhat limited in utility, particularly in the left subphrenic space, and CT scanning remains the technique with highest resolution. These noninvasive imaging techniques also have the potential for directed percutaneous catheter drainage.