Two cases of coexisting mature teratoma and thecoma are reported. In Case 1, a 36-year-old woman presented with severe genital bleeding and an ovarian tumor, 12 x 9 cm in size, was found. In Case 2, a 48-year-old postmenopausal woman presented with severe lower abdominal pain and an ovarian tumor, 15 x 11 cm in size, was detected. Macroscopically, the resected tumors of both cases showed a unilocular cystic tumor adjacent to a solid tumor. Microscopically, the cystic tumors were composed of cutaneous tissues and the solid tumors consisted of spindle cells with lipid-rich cytoplasm, arranged in interlacing bundles. The cystic tumor and the solid tumor were completely separate and no transitional features were recognized histologically.