One hundred twelve CT scans of 52 patients who were receiving treatment for neuroblastoma were reviewed for accuracy, and findings were correlated with data obtained from other imaging tests, physical examinations, laboratory tests, biopsies, surgery, and long-term clinical follow-up. CT was the most sensitive imaging test for tumor recurrence (85% detection rate), and it was also the most versatile in the ability to define recurrent disease in the retroperitoneum, liver, cranium, mediastinum, lymph nodes, and skeleton. All 30 tumor recurrences were detected by the combination of CT, bone-marrow biopsy, and selected spot radiographs at the sites of pain. CT was accurate and clinically useful both for assessing tumor response to therapy and for predicting findings at "second look" surgery (accuracy, 94%). CT is relatively cost effective by substituting for a more expensive but less accurate combination of competitive imaging studies.