Worldwide, breast cancer is the leading type of cancer in women. Among Egyptian women breast cancer showed the highest frequencies among all cancers. Docetaxel (DCX) is one of the chemotherapy medication used to treat breast cancer which mainly metabolized in the liver by cytochrome3A4. The present study was conducted to study pharmacokinetic and pharmacodynamic properties of DCX in Egyptian breast cancer patients and the interpatient variability of cytochrome3A4 activity, as estimated using urinary metabolites of exogenous cortisol. The practical work was take place in NCI, Cairo University, Egypt.