Single and repeated oral administration of the water extracts of Spergularia purpurea (SP) at a dose of 10 mg/kg were tested on hypoglycaemic activity in normal and streptozotocin-induced diabetic rats. In normal rats, the water extract of SP decreased significantly the plasma glucose levels 4 h after single oral administration (P<0.01), and one week after repeated oral administration (P<0.05). A significant decrease of plasma glucose levels was observed 6 h after a single oral administration of the water extract of S. purpurea in severe hyperglycaemic rats (n=6) from 22.78+/-0.60 to 11.21+/-0.49 mmol/l (P<0.001). On other hand, water extract of S. purpurea normalised plasma glucose levels after two weeks of repeated oral administration in diabetic rats; 24.05+/-1.16 versus 7.18+/-0.51 mmol/l (P<0.001) at the start and 2 weeks after water extract administration, respectively. We conclude that the water extract of SP induces hypoglycaemic activity when administered orally in normal and STZ diabetic rats. In order to determine the active principle (s) responsible of the hypoglycaemic effect, preliminary phytochemical analysis of the water extract has been investigated.