Rifaximin, an oral antibiotic marketed as tablets, does not have dissolution method described either in official compendiums or literature. This lack of knowledge blinds the real rate of drug availability. Thus, all potentialities of the active principle are not enough if it is trapped in its formulation or it is released erroneously. The absence of dissolution method can reduce the drug to the level of an adjuvant. Therefore, the objective of this study was to develop and validate a successful dissolution method for the evaluation of rifaximin tablets. The method contemplated the parameters for linearity, selectivity, precision, accuracy and robustness. It was found that for the dissolution of the tablets of rifaximin of 200 mg, paddle apparatus at 50 rpm and 900 mL of acetate buffer of pH 5.0 + 0.2 % SLS as dissolution medium are optimum conditions. The method presented is useful and can be applied for the routine quality control of tablets of rifaximin