The urban operation, urbanistical instrument defined by the City Statute, presents itself as a possibility to make interventions in the city viable, with the participation of the public and private sectors. Although federal and municipal legislation aim at the defense of the collective interest in detriment of the private, recognizing the right of all to the city, the laws show impressions that can permit deviations from these objectives. This can be verified in the application of this instrument in the county of Belo Horizonte, capital of the State of Minas Gerais. When analyzing two proposals of urban operation, seeking to identify the behavior of the involved parts, especially of the real estate agents and the State, in face of the greatest liberty of negotiation in the flexibilization of regulations of the use and occupation of land, it is found that various aspects of legal texts reveal tendencies to benefit, in greater scale, the private initiative. Thus, the efficiency of this instrument can be questioned in the promotion of urban development with social justice.