Twenty seven corn cultivars from the PCCMCA (Central America Cooperative Improvement Program) test were planted at two dates during 1982-83 at Isabela, Puerto Rico. The combined analysis of variance showed that there were significant differences between planting dates for grain yield, midbloom, leaf area index and rust reaction. Differences among cultivars were observed for all traits except test weight. Cultivar TICO V-6 from Costa Rica produced the highest grain yield (over 6 tons ha-1) at both planting dates.