Introduction: Oxidative stress induced by alloxan has been shown to damage pancreatic beta cell and produce hyperglycemia in rats. Hence the present investigation has designed to appraise antidiabetic and antioxidant principle of the methanolic extract of Marsilea quadrifolia (MEMQ). Methods: Hypoglycemic effect was evaluated in alloxan induced diabetic rat. The oral administration of plant extract at a dose of 300 mg/kg body weight was given to fasting glucose loaded rat with regard to normal control during 1 hr. study period and in alloxan induced (110 mg/kg body weight i.p.) diabetic rat in comparison with reference drug Metformin Hydrochloride (100 mg/kg) during 3 days study period. The antioxidant potential of MEMQ was checked by qualitative method and quantitatively through DPPH(1,1- diphenyl-2-picryl-hydrazyl) scavenging assay at 517 nm. Total phenolic content, total antioxidant capacity and reducing power activity was also assayed. Results: Considerable drop in elevated blood glucose level was observed in the alloxan induced diabetic (p<0.05 & p<0.001) rat. At a dose of 300 mg/kg the extract showed glucose level reduction of 47.57% in alloxan induced rat while 44.38% was found for Metformin after 3 days. Antioxidant activity using DPPH was found to increase in a concentration dependent manner with an IC50 value of 96.37 ± 3.62μg/ml higher than the standard one, IC50 16.59±0.59μg/ml. Total phenolic content was found 165.75 ± 0.961 mg/g in GAE and the total antioxidant capacity was equivalents of ascorbic acid (224.90 ± 1.42 mg/g). Conclusions: In all ways the extract showed significant antidiabetic and antioxidative potency. The present investigation suggests that MEMQ may be a potential source of natural antioxidant with good hypoglycemic activity.