The maintenance of seed viability during storage is influenced by several factors related to the species and to the environment. This work aimed to determine the viability of Mimosa caesalpiniifolia seeds from unripe and ripe fruits stored at different temperatures (ambient, 10 ºC, 0 ºC and -21 ºC). For this, the germination performance of the seeds was evaluated at 0, 3, 6 and 12 months of storage. The experimental design was completely randomized, with four replicates of 25 seeds per treatment. The variables evaluated were: number of germinated seeds, number of hard seeds, number of unviable seeds and number of normal seedlings. The storage potential of M. caesalpiniifolia seeds depends on the fruit maturity stage. Seeds from unripe fruits without drying do not tolerate storage. Seeds from unripe fruits with drying at 15% water content maintain viability, for 12 months, when stored at a temperature of 10 °C. Seeds from ripe fruits without drying maintain viability, for 12 months, when stored at temperatures of 0 °C and 10 °C.