PIK3CA mutations activate the PI3K-PTEN-AKT pathway which is downstream from both the EGFR and RAS-RAF-MAPK pathways. The somatic mutations found thus far in PIK3CA are oncogenic, and the majority of them are clustered within exon 9 and 20 (helical and kinase domains). Activating mutations in PIK3CA are found in a wide variety of human cancers including up to 5% of renal cell carcinomas. The role of PIK3CA mutations as prognosticators of outcome or predictors of therapeutic response awaits further evaluation. Clinical trials are available for patients with PIK3CA mutated tumors.