Background/Aim. The beneficial effects of medicinal plants are well-known from the ancient times. However, expansion of phytopharmacy and phytotherapy occured during the last decades. Medicinal plants can absorb environmental contaminants from the ground and consequently may cause harmful effects on human health. Quality control usually comprises standard methodology which includes macroscopic identification and examination of active ingredients. Additionaly, there is a permanent need to control the level of pollutants in herbs, with a particular attention to the level of toxic metals. In this study we estimated the level of contamination by determining the content of cadmium (Cd) in the herbs of Hypericum perforatum and Thymus serpyllum collected from the different localities of the mountains Rtanj and Ozren. Methods. Herbs of investigated plants were collected during July 2005 from various localities of Rtanj and Ozren mountains. After drying, homogenization and mineralization, Cd content was determined by atomic absorption spectrophotometry. Results. The obtained results show that Cd content varies significantly in Hypericum perforatum samples collected. The lowest Cd level was found in samples from the one of Rtanj localities (0.25 mg Cd/kg), while the highest was observed in Hypericum perforatum from Ozren locality (1.24 mg/kg). Levels of Cd in the three of four investigated localities were higher than pro posed by WHO (0.3 mg/kg dried herb material). In all investigated samples of Thymus serpyllum herbs Cd levels were below the limit of detection of analytical method (0.2 mg Cd/kg dried materials). Conclusion. This work contributes to the issue of Cd content in Hypericum perforatum and Thymus serpyllum grown in localities of Rtanj and Ozren, and implies the importance for systemic control of Cd content in Hypericum species in order to provide safety of their preparations. Furthermore, regarding Cd toxicity, maximal permissible level of Cd in plant material should be evaluated and established concerning national legislative frame.