Delayed primary operation has been started since 1982 in our department and 19 cases of solid tumor in childhood were treated with this method. They included 11 cases of advanced neuroblastoma, 5 cases of hepatoblastoma and 3 cases of yolk sac tumor in sacrococcygeal area. We discussed effectiveness of preoperative chemotherapy to the primary tumor and metastatic lesions, the best timing of operation after chemotherapy and the operative technique in delayed primary operation. Preoperative chemotherapy were useful in almost all cases of delayed primary operation, so the primary lesion and lymph nodes metastases were removed easily. We recommended it was the best timing of operation when 2 or 3 courses of preoperative chemotherapy were finished. CUSA (Cavitron Ultrasonic Surgical Aspirator) was the useful instrument to remove the primary tumor and lymph node metastases completely in advanced neuroblastoma preserving both kidneys.