Clear cell carcinoma (CCC) and uterine papillary serous carcinoma (UPSC) are aggressive variants of endometrial carcinoma that may coexist or share some clinicopathologic features suggesting a similar biologic spectrum and the need for a common therapeutic approach. Twenty-nine cases of pathologic FIGO stage I and II CCC and 47 cases of FIGO stage I and II UPSC seen and treated at Yale-New Haven Hospital were reviewed, and the survival rates with regard to various pathological parameters were compared. Both groups of patients had similar clinical profiles with respect to presentation, age, weight, and medical problems. The 5-year survival for pathologic stage I patients with CCC was 72% and for those with UPSC 44%. The 5-year survival for pathologic stage II patients with CCC was 59% and for those with UPSC 32%. Analysis of survival showed that the depth of myometrial invasion, the presence of vascular space invasion, and the admixture of endometrioid features did not influence survival in either group of patients. In CCC, survival was also not influenced by the predominant histologic pattern, i.e., papillary versus nonpapillary. The results of this study suggest that early stage CCC and UPSC have similar clinicopathologic profiles, suggesting the need for aggressive approaches including a staging laparotomy and possibly similar therapy. However, the stage I CCC patients had a significantly better survival than the stage I UPSC patients.