71 With the public’s Envi ronmental awareness and the significance of its protection, in recent times pressurized the textile industry for use of natural colorants because they are ecofriendly, biodegradable and low in toxicity. In this paper, Berberine as a natural cationic colora nt extracted from Berberis vulgaris with soxhlet and ethanol as solvent. Then extracted natural dye apply to cotton fabrics. It was found that the exhaustion of Berberine on cotton fabric pretreated with tannic acid and Tartar emetic was increased compared to untreated fabrics. the dyeing temperature, the dye bath pH and duration on dyeing quality were studied. The optimum dyeing temperature was 50 ? and the optimum dye bath pH was 4 - 4.5 . The equi librium time obtained 60 minutes. The kinetic study of dye exh austion showed a small time of half dyeing and consequently rate of dyeing obtained fast. The adsorption isotherms showed dual, both Freundlich and Langmuir type of adsorption isotherm . The thermodynamic parameters were obtained. Due to berberine’s charac teristic of cationic quaternary ammonium salt, it can use in antimicrobial finishing. the dyed sample with 10% owf Berberine showed very effective antimicrobial functions about 99.9% of bacterial reduction against Gram - p ositive bacteria .