In the present study, the methanol, acetone and chloroform extracts of the lichen Usnea florida (L.) were tested for antibacterial, antifungal and antituberculosis potential. The disk diffusion method was used for the investigation of antimicrobial activity and the minimal inhibitory concentration was identified against thirteen species of bacteria, four species of yeasts, and eight species of fungi. Strong activity toward bacteria and yeasts was determined in all extracts. However, there was no strong activity toward filamentous fungi. Bioactive substances of lichen Usnea florida were demonstrated with the bio autography in thin layer chromatography. Thamnolic acid was found to be an active substance with 200-400 mu g/ml concentration. As a result, the lichen may be used as a possible antimicrobial agent in various applications in the food industry and for the purpose of controlling different diseases.