Immortelle (Helichrysum italicum (Roth) G. Don) is a plant from the family of daisies (Asteraceae). It grows in the mediterranean and sub-mediterranean climate on rocky terrain and in rocky pastures. It is on the list of protected species in the Republic of Croatia. Since ancient times, it has been known for its antibacterial and antifungal properties. In literature, phenolic compounds are the most frequently cited compounds which give immortelle its medicinal properties. These are secondary metabolites with potent antioxidant activity. Exposing plants to stressful conditions results in the increased production of toxic oxygen derivatives, which include free radicals. Plants have developed effective defense mechanisms which protect them from destructive oxidative reactions. Phenolic compounds are included in this mechanisms and they prevent damage within the plant cells which are caused by free radicals and harmful environmental impacts. These properties of the phenolic compounds are applied in medicine as well as in cosmetic and food industries. The aim of this study is to determine how the different media pH values affects the amount of phenolic compounds and the antioxidant activity of Helichrysum italicum grown in vitro. For this research I used sprouts of Helichrysum italicum grown in vitro on media with different pH values. After lyophilization, the amount of anthocyanins, total phenolics, tannins as well as flavonoids were assessed in plant tissue. The antioxidant capacity of immortelle was also determined. Plants grown on MS media with a pH value of 8 had the highest amount of total phenols, tannins and flavonoids and plants grown on medium witha pH value of 7had the largest amountof anthocyanins . Most of the total phenols in the immortele are tannins followed by the flavonoids and a small amount of anthocyanins. The strongest antioxidant activity was shown in plants grown on MS media with a pH value of 8.