In the current study, we measured the mRNA expression of PIK3CA and PTEN genes in breast cancer tissue and compared them with their expression in normal breast tissue, and according to data of this study the PIKECA expression showed significantly higher in breast carcinoma tissue than in normal breast tissue, where the median value of PIK3CA expression in breast carcinoma was 42.35 whereas in normal tissue was 1.12 (P<0.001). This evidence concerns the gene PIK3CA and breast cancer.