Diabetes mellitus is considered as a major public health problem and one of the leading causes of deaths in the world today. There are many herbal preparations used in ayurvedic and other traditional systems of medicine which are claimed to have hypoglycaemic potential with fewer side effects. This study investigated the hypoglycaemic effect of tender leaves of the medicinal plant named Aporusa lindleyana.1 The hypoglycaemic effect of the methanolic leaf extract of A. lindleyana on fasting blood glucose level, random blood glucose level and the effect on oral glucose load were tested using three oral doses of the extract (100, 400, 800 mg/kg body weight) in normoglycaemic adult male Sprague-Dawley rats weighing 200-250 g (n=6 for each dose, control and reference drug). In determining the effect of fasting and random blood glucose level, glucose concentration was measured prior to the treatment and hourly for four hours.2 For the evaluation of glucose tolerance, blood was collected prior to the treatment and hourly for four hours after the administration of glucose load.2 Blood (0.25 ml) was collected from the tail vein of the rats under light ether anesthesia (about 1ml by inhalation route) using aseptic precautions, serum was separated and the glucose concentration was determined spectrophotometrically using Randox glucose oxidase assay kit. Ethics approval was obtained from the Ethics Review Committee of Faculty of Medicine, University of Colombo for animal experimentation. Results were statistically analyzed by ANOVA followed by Dunnett’s multiple comparison test and expressed as mean ± S.E.M. using Minitab 15 software. The results exhibit a dose dependent hypoglycaemic effect with lowest blood glucose level observed at 4 h after the treatment. All the three doses significantly reduce the fasting blood glucose level of rats at 4h after the treatment (Control vs. 100 mg/kg: 94.6±0.807 vs. 81.2±2.95 mg/dl, p<0.05; Control vs. 400 mg/kg: 94.6±0.807 vs. 77.8±2.80 mg/dl, p<0.05; Control vs. 800 mg/kg: 94.6±0.807 vs. 69.4±1.53 mg/dl, p< 0.05). Only intermediate and high doses show significant reduction in serum glucose level in normoglycaemic non fasted rats (Control vs. 400mg/kg: 129±3.00 vs. 114±2.63 mg/dl at 4h, p<0.05; Control vs. 800mg/kg: 129±3.00 vs. 113±3.03 mg/dl at 4h, p<0.05 ) and significant glucose tolerance when tested on oral glucose load (Control vs. 400mg/kg: 98.9±2.79 vs. 87.7±1.76 mg/dl at 4h, p<0.05; Control vs. 800 mg/kg: 98.9±2.79 vs. 85.2±1.18 mg/dl at 4h, p<0.05). According to the above results, it can be concluded that A.lindleyana leaves have hypoglycaemic activity since it significantly (p<0.05) reduces the blood glucose level in normoglycaemic rats and significantly (p<0.05) enhances the glucose tolerance.