Endodermal sinus tumors(EST) are generally recognized as a germ cell tumors with extraembryonic differentiation that resemble the endodermal sinus of the rat placenta. Like other germ cell tumors the primary EST may either occur in the gonads of in specific extragonadal sites. CT is the most accurate study in delineating the extent of primary and metastatic lesions particularly in the pelvis. Recently authors experienced six cases of the pathologically proven extragonadal endodermal sinus tumors in children and retrospecitively analyzed the radiological findings including the CT. The results were as follows: 1. Of the 6 cases of extragonadal EST, the primary lesion presented in the sacrococcygeal resion in 5 patients and liver in one patient. 2. There were 4 females and 2 males. Of the sacrococcygeal lesions 3 were females and 2 were males. 3. The age of presentation ranged from 9 months to 3 years of age (mean age = 21 months) 4. Conventional radiographic study of the sacroco cygeal lesion showed presacral, retrorectal soft tissue mass without calcification which extended into the buttock. CT revealed well circumscribed enchancing soft tissue mass with irregular central low density areas. 5. Primary EST of the liver revealed ill-defined inhomogeneous mixed echogenic mass (ultrasound) and ill-defined low density mass (CT). Angiography showed hypervascular mass with areas of necrosis and no evidence of portal vein invasion. A-V shunting was not present. 6. Regional lymph node metastasis was present at the time of diagnosis in 2 cases of sacrococcygeal EST. 7. Local recurrence of tumor was noted in 2 patients with sacroccygeal lesion after surgery and chemotherapy.