Birch sap and birch leaves extract have been screened for antimicrobial, phagocytosis-influencing, anti-inflammatory and antipyretic activity. No antimicrobial effects could be detected in the agar-diffusion test with staphylococcus as test strain, whereas birch sap exhibited some inhibitory effect on phagocytosis, which exceeded that of the citric acid added to the birch sap as preservative. In rats, only the high doses of 1 and 2 ml/100 g b.m. birch sap had a weak and short-lasting anti-inflammatory activity against the Carrageenin edema, whereas birch leaves extract proved to be ineffective. Fever induced by baker's yeast in rats was inhibited by birch leaves extract in the high dose of 4 ml/100 g b.m. significantly, but not by birch sap, and only for a short period. Acetylsalicyclic acid had a much higher anti-inflammatory and antipyretic activity. Altogether despite of detectable anti-inflammatory, antipyretic and phagocytosis-inhibiting effects of these birch products no therapeutic activity of importance compared with classical and modern antipyretics-analgetics can be demonstrated.