We documented tree species compositions and stand structures that developed naturally in 11-, 16-, 21-, 26- and 31-year-old teak (Tectona grandis L.) monoculture plantations in the Bago Mountains, Myanmar. Vegetation was surveyed in three sample sites located in reforestation areas. Within randomly deployed quadrats, we recorded tree species, top heights and diameters at breast height (dbh) for all individuals with dbh values ?4 cm. We identified 72 tree species across stand ages and found indicator species that were characteristic of mixed deciduous forests in the region. Calculated average Shannon-Wiener index values for the three sample sites showed that tree diversities were similar in the secondary forests studied. Associated tree regeneration accounted for 34?54% of planted stand densities and 19?38% of basal areas across the plantation chronosequence.