Highly sensitive spectrofluorimetric method was developed and validated for the determination of gabapentin in pure and pharmaceutical preparations. The method was based on nucleophilic substitution reaction of gabapentin with 4-fluoro-7-nitrobenzofurazan (NBD-F) in an alkaline medium (pH 9.5) to form a highly fluorescent derivative that was measured at 521 nm after excitation at 458 nm. The factors affecting the reaction was carefully studied and optimized. The method was successfully validated for linearity, limit of detection, limit of quantification, accuracy, precision, robustness and specificity. Under the optimized conditions, linear relationship with good correlation coefficient (0.9998) was found between the relative fluorescence intensity and gabapentin concentration in the range of 10-100 ng.mL(-1). The limit of detection and limit of quantification were 0.43 and 1.30 ng.mL(-1), respectively. The proposed method was successfully applied to the determination of gabapentin in its pharmaceutical capsules. The results obtained by the proposed method were comparable with those obtained by the official method. Statistical comparison by t- and F- tests revealed that there was no significant difference between the results of the two methods with respect to mean values and standard deviations at the 95% confidence level.