Computed tomographic (CT) characteristics of 45 residual masses in 30 patients with disseminated nonseminomatous testicular cancer treated with chemotherapy were correlated with histologic findings at surgery. Thirty-one masses were studied serially on pre- and postchemotherapy scans. At the time of tumor-reductive surgery, all patients had normal serum tumor markers (alpha-fetoprotein and human chorionic gonadotropin). Residual malignancy was found in 27% of patients, teratoma in 33%, and fibrosis or necrosis in 40%. The CT appearance of the masses--size, qualitative density, and change noted during the course of treatment--was insufficient to exclude the presence of residual malignancy or teratoma. An enlarging mass of psoas density occurred only once in this series; it contained malignancy. Other CT characteristics of residual masses had no greater than 50% correlation with the presence of malignancy. Histologic evaluation of residual masses remains necessary to guide further patient management.