Uterine carcinosarcoma (UCS) accounts for approximately 15% of uterine cancer-associated deaths in the United States. With lack of effective treatment modalities, identification of underlying molecular defects may allow the introduction of targeted treatments. The expression of AKT, epithelial growth factor receptor, C-Kit, and C-ErbB-2 were studied by immunohistochemistry and exons 9 and 20 of PIK3CA gene were sequences in a cohort of 37 UCS, including 23 early-stage (I and II) and 14 late-stage (III and IV) tumors. Twenty-three (62%) of the UCS were homologous; the reminder contained heterologous elements. The carcinomatous component was pure serous carcinoma in 13 (35%), endometrioid in 12 (32%) cases. An immunostaining score ranging from 0 to (6+) was calculated for AKT, epithelial growth factor receptor, and C-Kit. C-ErbB-2 staining was scored by American Society of Clinical Oncology/College of American Pathologists criteria. AKT staining was seen in 35/37 cases with an immunostaining score ranging from (2+) to (5+). AKT was expressed significantly more in the early-stage than late-stage disease (P=0.016). The expression of AKT in the epithelial component was associated with the survival (P=0.026). Epithelial growth factor receptor was positive in 21/37 cases. Only 8 cases showed (≤3+) immunostaining score with C-Kit. C-ErbB-2 immunostain was (3+) in only 1 case. An H1047R mutation on PIK3CA gene was detected in both carcinomatous and sarcomatous components in a single case. These results indicate that AKT pathway may be important in pathogenesis of UCS. Further studies with larger cohorts are warranted to confirm the observed associations in this study.