The pharmacological researches have been performed for Usnea barbata and Usnea hirta species using hydroalcoholic extracts. The acute toxicity has been determined and the following LD50 have been obtained: i. p. Usnea barbata 22.53g vegetal material/kg b. w.; Usnea hirta 21.02g vegetal material/kg b. w.; i. v. Usnea barbata 7.43 vegetal material/kg b. w.; Usnea hirta 4.52g vegetal material/kg b. w.; per os up to 32g vegetal material/kg b. w. no mortality has been recorded. It has been demonstrated that the antiinflammatory activity was comparable, sometimes superior to the phenylbutazone and hydrocortisone hemisuccinate; the analgesic activity was close to the noraminophenazone; the antipyretic activity was equal, sometimes superior to the aminophenazone. In Romania, Usnea barbata was mentioned in 1929 among the plants known by Romanian people with popular names: "Bear's beard", "Trees' dandruff", "Woman's long hair" (1). "Farmacia naturii" (2) and "Flora medicinală a Romaniei" (3) have mentioned that Usnea barbata (L) Mott contains usnic acid-substance with broad antibiotic spectrum. Lichens have made the subject of the multiple studies because of their old medical use (4). Besides the antibiotic properties noticed at lichens products (4) there have been discovered the following pharmacological actions: antiinflammatory (5), antitumoural, immunostimulatory (6, 7, 8, 9). The results of the researches made on lichens family within Romania's spontaneous flora (10) have determined us to study the two species: Usnea barbata (L) Mott and Usnea hirta (L) Wigg.