This work was conducted to verify the influence of size on germination of Caesalpinia echinata seeds. The experiment was carried out in Instituto de Botânica, São Paulo, Brazil, in 1991, under germinator conditions at 25°C with 12 hour photoperiod and in greenhouse at 30°C. The seeds used for germination tests were previously separated according to size and were tested as follows: 1) small seeds (with 0.26g of average weight); 2) medium seeds (0.37g); and 3) large seeds (0.48g). Evalutaion was based on germination percentage. The statistical model was entirely randomized, with three treatments and five replications. Results under laboratory conditions showed significant differences between treatments at 5% probability; in greenhouse conditions, no significant differences appeared.