Sparfloxacin is a quinolone carboxylic acid derivative that shows activity as an antimicrobial agent, against a wide range of Gram-negative and Gram-positive organisms. It is clinically useful for the treatment of urinary tract infections, respiratory tract infections and gynecological infections. In this study in vitro drug-drug interaction of sparfloxacin has been carried out with famotidine and ranitidine. For these studies a two-component spectrophotometric process has been developed for sparfloxacin assay in the presence of famotidine or ranitidine. The reproducibility of the method is within ±5%. The technique has been applied to the development of sparfloxacin in methanol. The interaction studies of sparfloxacin with ranitidine and famotidine were carried out in methanol and methanol: Water mixtures (30:70, v/v; 50:50, v/v) and the kinetics of sparfloxacin degradation were evaluated in the presence and absence of famotidine and ranitidine. The decrease in the rate of degradation of sparfloxacin in the presence of famotidine or ranitidine, compared to that of sparfloxacin alone, indicated the possibility of interaction between the sparfloxacin and famotidine or ranitidine. The Thin layer chromatography (TLC) of the degraded solution showed the presence of a degradation product of sparfloxacin. The studies show that complexation with famotidine or ranitidine may affect the bioavailability of sparfloxacin.