Resumo. ABSTRACT This study tested the influence of mechanical and thermal scarification methods on emergence and establishment of Guazuma ulmifolia seedlings. Seeds were subjected to pre-germination treatments of (1) mechanical scarification (sandpaper), and (2) thermal scarification (hot water), in addition to the control treatment (3) from which the seeds were left intact. The thermal scarification treatment differed from the other treatments featuring the largest number of seedling emergence (70%). The seeds treated with sandpaper achieved the lowest emergence percentage not differing from the control treatment. For the germination speed index no significant difference between treatments has been verified and the emergence peak was between the 13 rd and 15 th days of incubation in all treatments. In the establishment, the seedlings growth (height, diameter and number of leaves and nodes) presented differences between the treatments. It was observed further development of seedlings after their seeds go through thermal scarification. Therefore, scarification with hot water is the most appropriate method for breaking the dormancy of seeds of Guazuma ulmifolia , providing more vigorous seedlings.