In the present study, Polysaccharide mucilage derived from the seeds of fenugreek, Trigonella foenum-graceum L (family Leguminosae) was investigated as disintegrant for use in mouth dissolving tablet formulations containing metformin hydrochloride. Mucilage extracted from fenugreek seeds were subjected to toxicity studies, it showed that extracted mucilage is devoid of toxicity. Fast disintegrating tablet (FDT) of metformin HCl was formulated using different concentration (2, 4, 6 8 and 10% w/w) of natural disintegrant viz; isolated mucilage of fenugreek seed and synthetic superdisintegrants like croscarmellose sodium and were compared. Disintegration time and drug release were taken as the basis to optimize the rapidly disintegrating tablet. Prepared tablets were evaluated for thickness, hardness, friability, uniformity of weight, disintegration time, wetting time and dissolution study. The formulated tablets had good appearance and better drug release properties as compared to the marketed conventional tablets. Fenugreek mucilage in the concentration of 4% gives shorter disintegration in 15 sec. and shows 100% drug release within 18 min. is selected as the optimized formulation (F2). Hence, the present study revealed that this natural disintegrant (fenugreek mucilage) showed better disintegrating property than the most widely used synthetic superdisintegrants like Ac-di-sol in the formulations of FDTs. Studies indicated that the extracted mucilage is a good pharmaceutical adjuvant, specifically a disintegrating agent. Optimized formulation was subjected to stability studies as per ICH guidelines at 250 and 65% RH, 40 and 75% RH showed insignificant change in hardness, disintegration time and in vitro drug release at the end of three months.