The aqueous extract of Artemisia herba-alba Asso. (Compositae) produced an initial hyperglycaemia which was followed by hypoglycaemia in normoglycaemic and alloxan-treated rabbits and mice. The extract (0.39 g/kg) significantly increased gastrointestinal transit time and the reaction time to thermal stimuli but had no effect on the activity of alkaline phosphatase or concentrations of creatinine and urea in plasma. Histopathological examination indicated mild hydropic degeneration in hepatocytes and proximal convoluted tubules. The duodenum showed mild oedema of the substantia of the mucosal propria. The plant extract showed weak antimicrobial activity.