Rosa canina L. fruits (Rosaceae) are used to treat diabetes in Anatolia traditionally. In this study, the ethanol extract of R. canina fruits and its fractions were screened for their antioxidant, hypoglycaemic and antidiabetic activities. The ethanol extract that was administered for 7 days possessed a remarkable hypoglycemic effect at 250 mg/kg dose in streptozotocin (STZ) induced diabetic rats. Then it was fractionated through successive solvent extractions to yield CHCl3 Fr., EtOAc Fr., n-BuOH Fr. and R-H2O Fr. respectively. These fractions were administrated to normal plus glucose hyperglycemic rats. Additionally the subacute antidiabetic activities of the fractions were studied in diabetic rats for 7 days. The experimental data indicated that R-H2O Fr. possessed significant antidiabetic activity (50-62%) in diabetic rats. Also, a minor hypoglycemic effect was observed in normoglycemic plus glucose-hyperglycemic animals treated with R-H2O Fr. (15%). In vitro antioxidant experiments revealed that EtOAc Fr. showed the highest radical scavenging activity on DPPH (79.5 +/- 0.4%), whereas CHCl3 Fr. exhibited the maximum reducing power. The highest total phenolic content was observed in CHCl3 Fr. (18.5 +/- 0.6% gallic acid equivalent g/g fraction) but no correlation was observed between the antidiabetic activity of fractions and their phenolic contents. Our findings support the traditional usage of R. canina fruits as a folk remedy in the treatment of diabetes in Turkey.