A simple and accurate colorimetric method was developed for the quantification of Gabapentin (GP) in bulk and pharmaceutical formulations. The method was based on the coupling of GP with ascorbic acid to give a colored product having analytically useful maxima at 390 and 531 nm. Factors affecting the color development and stability were optimized and incorporated in the procedure. Regression analysis of Beer's plot showed good correlation (not less than 0.999) in a concentration range of 12-60 μg/mL. The detection and quantification limits were 0.73μg/ml and 1.69μg/ml, 2.43μg/ml and 5.65μg/ml at 390nm and 531nm, respectively. The average recovery for the commercial preparation (Gabapentin 400mg capsule) was 100.06 ±1.02% and 102.83±5.49%; n=3 at 390nm and 531nm, which reflected no interference by the capsules additives. Based on the molar ratio, the reaction stoichiometry was found to be 1:1.