Indexes of market concentration were calculated using data from inspected slaughterhouses in the State of São Paulo, Brazil, from 1978 to 1989. The Hirschman-Herfíndahl (H) and the Gini (G) indexes showed statistical tendency to increase. The four firms concentration index of the four greatest slaughterhouses (C4) showed no statistical tendency to increase while the concentration indexes of the eight greatest (C8) and of the sixteen greatest (C16) showed statistical tendency to increase from 1980 on. It can be concluded that the market concentration among the chicken slaughterhouses was more or less stable with small tendency to increase from the eigth smallest slaughterhouses below. For the analyzed time period, the retail's relative price and the producer's gain decreased.
chicken meat; market concentration; industrial organization