This research investigated the effect of water on seed germination of jacarandá-da-Bahia (Dalbergia nigra) and cedro (Cedrela fissilis). The work was done in two steps: In the first one, seeds from both species were originally placed in water potencial of -2 and -4 bars for cedro, and additional water potencial treatments of -2, -4, -6 and -8 bars for japarandá-da-Bahia. On the second step, pre-imbibition was done by seed imbibition in water potencial of -6 bars for cedro and -10 bars for jacarandá. After some period of time seed was returned to original osmotic potencial in cases of little or no germination. The results showed that in both species, the percentage of final germination was reduced and the beginning of germination was delayed by increasing asmatic potencial. The pre-imbibition increased speed and percentage of final germination where originally had occurred little or no germination.