Palpation of an abdominal mass in an infant or child presents a challenging problem in diagnosis and treatment. We reviewed the data on 166 patients under age 15 years who admitted to Ped. Dept. of PMC due to palpable abdominal mass in Jan. 1972-July 1977. The results are as follows 1. Of the 57 surgical cases, pathologically confirmed abdominal tumors were 39 cases. Of the 20 retroperitoneal tumors, Wilms tumors were 13 cases, neuroblastomas were 3 cases, polycystic kidney was 1 case, and retroperitoneal teratoma was 1 case. Of the 19 intraperitonel tumors, hepatomas were 3 cases, hepatoblastoma was 1 case, choledocal cysts were 3 cases, mesenteric and omental cysts were 4 cases, malignant lymphomas were 4 cases and ovarian cysts were 3 cases. Other surgical diseases were 2 cases of ascariasis and 2 cases of bezoar. 2. Medical cases were as follows : 35 cases of leukemia, 15 cases of infectious hepatitis, 14 cases of congenital syphilis 7 cases of liver cirrhosis 7 cases of lirerabscesses, 4 cases of miliary Tbc., 3 cases of congenital spherocytosis, 1 case of cryptococosis, I case of osteopetrosis and 1 case of erythroblastosis fetalis. 3. In age distribution, almost all cases(94%) of Wilms tumor and neuroblastoma were under age of 4 and half of medical cases in infancy were congenital syphilis. 4. Of the pathologically confirmed 39 abdominal tumors, 20 cases were retroperitoneal tumor and 19 cases were intraperitoneal tumor. Of the 20 retroperitonel tumor cases, 16 cases were renal origin, 3 cases were adrenal origin, and 1 case was teratoma. Of the 19 intraperitoneal tum orcases, 8 cases were hepatobiliary origin, 3 cases were ovary origin, 4 cases were omental and mesenteric origin and 4 cases were lymphatics origin. 5. Of the 39 abdominal tumor cases, 34 cases (87%) visited the hospital with the chief complaint of palpable abdominal mass. But, of the 94 medical cases, only 16 cases(17%) visited the hospital with the chief complaint of palpable abdominal mass. 6. In some cases presumptive diagnosis on the base of history taking, physical examination, chest X-ray, simple abdominal X-ray. Peripheral blood findings on admission were uncorrect. In 1 case of Wilms tumor, we suspected liver abscess on admission. In 1/3 case of intraperitoneal tumors, we suspected retroperitoneal tumor on admission. We suspected lymphoma on admission in 1 case of ascariasis and 1 case of bezoar. We misdiagnoed 1 case of miliary Tbc. As hepatoma, 1 case of liver cirrhosis as retroperitoneal tumor and 1 case of congenital syphilis as retroperitoneal tumor on admission. 7. In the treatment of malignant abdominal tumor, we tried all possible measures such as surgery, chemotherapy, and radiation therapy. But prognosis of all malignant abdominal tumors were very poor. Only 1 case of Wilms tumor and 1 case of hepatoblastoma were survived at the time of review.