The medicinal and tree species Luehea divaricata is known as ‘açoita-cavalo’ and widely used for wood, reclamation, and in popular medicine. The aim of this study was to evaluate the antiproliferative and genotoxic effects of infusions of two populations of this species on the Allium cepa cell cycle. Cells of root tips of Allium cepa were used as an in vivo test system for monitoring the genotoxicity of this medicinal plant. Leaves and bark of two populations of Luehea divaricata were collected during the vegetative stage and used to prepare infusions in two concentrations: for the leaves (6 g/L and 30 g/L) and two concentrations for the bark (32 g/L and 160 g/L), using distilled water as negative control and glyphosate 3% as positive control. For this study, 10 groups of four bulbs were utilized, with one group of bulbs for each treatment. The slides were prepared by the squashing technique, scoring 4000 cells for each group of bulbs. The mitotic index (MI) was calculated and then a statistical analysis was performed using chi-square (χ). The results showed that Luehea divaricata infusions in both populations caused a reduction of MI compared to control, and in both analyzed concentrations there was no significant genotoxic effect in comparison to the negative control, however there was a significant difference in relation to the positive control for both populations. The antiproliferative effect of leaf extracts increased with a greater concentration and among bark extracts no significant difference occurred between the two concentrations. The studied populations did not show genetic variability regarding the antiproliferative effect.