This article evaluates the evolution of productivity, specialization and concentration of milk production in microregions of Rio Grande do Sul in the period 1990 to 2009. Productivity is measured by the ratio between milk production and the number of cows milked, the specialization is calculated from the location quotient (QL) and concentration is determined by the location Gini (GL), according to the geographical division of microregions of IBGE. The survey results showed that increases productivity, specialization and concentration in milk production, with emphasis on microregions of Três Passos, with QL equal to 2,33 in 2008, and Passo Fundo, with productivity of 4.197 liters/cow in 2009. The location Gini also showed a significant growth in the period 1990-2009 (56.25%), went from 0.32 to 0.50.