Many children with malignant diseases who present with an anterior mediastinal mass must undergo general anesthesia for tissue diagnosis or tumor resection. One hundred sixty-three pediatric patients over a period of 6 yr were admitted to Memorial Sloan-Kettering Cancer Center with a diagnosis of anterior mediastinal mass. Forty four of these patients required surgery and their records were reviewed. In recent years perioperative radiation therapy has been advocated for this patient group prior to their receiving general anesthesia. If a tissue diagnosis has not been made, preoperative radiation therapy may distort histologic findings and prevent accurate diagnosis. All patients with an anterior mediastinal mass who must receive general anesthesia in our institution do so prior to treatment with radiation or chemotherapy even in the presence of cardiovascular or respiratory symptoms. No patient died or sustained permanent injury as a result of their anesthetic or operative experience. Two patients who experienced difficulty on induction of anesthesia required tracheal intubation with a rigid bronchoscope. Two patients developed airway obstruction during anesthetic maintenance that was corrected with changes in patient position. Four patients were unable to have their tracheas extubated at the conclusion of surgery and one patient required tracheal reintubation in the immediate postoperative period. These patients were treated with radiation therapy and chemotherapy after tissue for diagnosis had been obtained. The authors conclude that in the absence of life-threatening preoperative airway obstruction and severe clinical symptoms general anesthesia may be safely induced prior to radiation therapy.