The production of meat pork has experienced a significant growth between 1975 and 2004. The base of this expansion is the concentration that exhibits this industry. In this study, the power of monopoly in the context of an oligopolical market with dominant firm of the Stackelberg type is estimated. The estimation of monopoly is made indirectly through the estimation of the elasticity of residual demand of the dominant company, under diverse levels of participation of the market. A system of equations of supply and demand of pork meat, applied to the indicated period, is used. A market power that evolves was obtained in direct form with the quota of market of the reference company, been of equal levels from 0.2% to 18.2%. One concludes that, according to the available antecedents, the power of monopoly of the dominant firm in 2000, reached 7%.