In this work, we carried out chromosome counts of four species of Campomanesia (C. adamantium, C. guaviroba, C. phaea and C pubescens) and four of Psidum (P. acutangulum, P. cattleyanum, P. cinereum and P. guajava) from different populations. In Campomanesia, 2n=22 was found in all of the species analyzed, and no polyploidy was seen, For Psidium, only P. guajava had 2n=22 and another three species had 2n=44. No abnormalities in meiosis were observed. High levels of pollen stainability (> 80%) was seen in all species. About 50% of Myrtinae species were polyploid, indicating the importance of polyploidy in the evolution of this group.591713