Micromeria croatica, like many other species belonging to the Lamiaceae family, is characterized by good antioxidant activity. To avoid the exploitation of natural plant populations, it is recommended to grow them in vitro culture. The present study aimed to examine and compare the antioxidant potential of M. croatica obtain through nodal culture in vitro and collected from natural habitats. Different antioxidant methods were used: DPPH, ABTS, total reducing power, total phenol content, and flavonoid content. The obtained results indicate that the cultivation of plants by the in vitro culture technique stimulates the synthesis of secondary metabolites that promote antioxidant activity. It is increased in micropropagated plants primarily due to the increased phenol content by 136%. The possibility to test and then apply in practice the biological activity of the herb M. croatica is limited by the fact that the species is a local endemic.