In recent years, there has been an increasing awareness of the genotoxic potential of a wide variety of synthetic hormones that widely used in medicine largely for their potent anti-inflammatory and immunosuppressive activities. Hydrocortisone, synthetic preparation of steroid hormone cortisol, is chosen for the present study for several reasons:1) it is widely used for treatment of a variety of inflammation, asthma, allergic, cancer and immune diseases; 2) very few data are available concerning the genotoxic hazard of hydrocortisone in mice. Considering this, the present work was carried out to study the hypothesis that hydrocortisone induce genotoxic effect in mice using different mutagenic end points. As well as, the study was planned to evaluate the hypothesis that green tea extract inhibit DNA damage induced by hydrocortisone. To achieve these hypotheses, the study was designed by given mice different doses of drug and plant extract in single and repeated treatment regimens.