Masses arising from the ovary are very rare in children. Forty-five patients with ovarian masses presenting to the New 
Children's Hospital, Cairo University between 1991 and 2000 were studied. All patients were between 20 days and 17years, with a mean age of 5.8 years. Only one case of complex corpus luteum cyst was diagnosed antenatally. Ultrasonography and tomographic scanning were performed for all cases together with hormonal assays in some patients. Surgical intervention was not performed in four cases of follicular cysts. 
Among those with benign diseases (34 cases), two had simple cysts, 13 had follicular cysts, a case of corpus luteum cyst, 
2 had serous cystadenoma, one had Brenner' s tumor, 3 cases of granulosa cell tumor and 12 cases of benign cystic 
teratoma.The malignant lesions (11 cases) included 6 cases of immature teratomas , 3 cases of endodermal sinus tumor , one case of dysgerminoma and a case of embryonal carcinoma . Most cases presented with abdominal masses or pains. Isosexual pseudoprecocious puberty occurred in eight patients, torsion resulted in three cases. All patients remained disease-free except two cases: an immature teratoma and an endodermal sinus tumors who died postoperatively .