Resumo. In forest management, it is important to project diametric distribution along the cutting cycle to subsidize the most suitable silvicultural techniques to forest structure. The aim of this work was to project diametric distribution along the cutting cycle using Markov Transition Matrix. In 1979, selective harvest was performed with an intensity of 72.5 m3 ha-1, in a 64 ha area in ‘Floresta Nacional do Tapajós’ - Pará state (PA). In 1981, 36 permanent plots of 50m x 50m were randomly installed and measured successively in 1982, 1983, 1985, 1987, 1992, 1997, 2007, 2010 and 2012. For the projection, two transition matrices were used: one with time interval of one year (1981 to 1982) and another of two years (1981 to 1983). All projections showed diametric distribution in inverted “J” form, with small discontinuity last year (2012). There was adherence of diametric distribution at 5% significance between observed and estimated data, up to 11 years of projection. Transition matrix can be used to project diametric distribution after harvest in short periods of time after the forest harvest.