One hundred eighty-five patients who underwent surgery within 6 months of completing chemotherapy were identified from 360 patients with nonseminomatous germ cell tumors (NSGCT) treated with Memorial Hospital front-line cisplatin- or carboplatin-based combination chemotherapy protocols between 1979 and 1988. Clinical, pathologic, and radiologic features were correlated with the pathologic findings at surgery. The size of a residual retroperitoneal mass, the degree of shrinkage that occurred with chemotherapy, and the presence of teratomatous elements in pretreatment pathology specimens were each correlated with the pathologic findings of retroperitoneal resections after chemotherapy. Multivariable logistic regression analysis of those undergoing retroperitoneal resections identified the size and shrinkage of the residual mass and the prechemotherapy lactate dehydrogenase (LDH) and alphafetoprotein (AFP) levels as the best predictors of finding only necrotic debris. No factors could be found, however, that could selectively exclude patients who had residual viable malignancy or teratoma in the retroperitoneum. Of 39 patients with residual retroperitoneal masses measuring less than or equal to 1.5 cm in maximal diameter, three had residual malignancy and five had teratoma resected. No factors were identified for residual lung or mediastinal masses that could be used to select a group of patients who could safely avoid surgery. If serum markers have normalized after chemotherapy for NSGCT, resection of all residual abnormalities on imaging studies of the retroperitoneum, lungs, and mediastinum is recommended. In addition, retroperitoneal lymph node dissection (RPLND) is recommended for all patients with initial bulky metastases (greater than or equal to 3 cm in diameter) in the retroperitoneum, irrespective of the findings of postchemotherapy computed tomography (CT).