To identify the incidence and spread pattern of parametrial involvement in endometrial carcinomas, resected parametria in 91 patients who underwent radical or modified radical hysterectomy with pelvic lymphadenectomy were histologically examined. The relationship between parametrial involvement and other histopathological features including histological type, tumor grade, depth of myometrial invasion, lymph-vascular space invasion, cervical involvement, adnexal metastasis, and lymph node metastasis was studied. Parametrial involvement was histologically demonstrated in 12 (13.2%) of the 91 cases. There were 2 patterns of spread: direct invasion of cancer cells to the parametrial connective tissue (5 cases) and lymphatic involvement within the parametrium (7 cases). According to the FIGO surgical stage, parametrial involvement was found in none (0%) of 48 patients in Stage I, 3 (11.5%) of 26 in Stage II, and 9 (52.9%) of 17 in Stage III. Among histopathological variables, the presence of parametrial involvement was significantly correlated with deep myometrial invasion and lymph-vascular space invasion in the myometrium. Multivariate analysis revealed that parametrial involvement significantly contributed to the poor prognosis in Stage II and III patients.