Two field trials were conducted one during 2012 wet season and another in 2012/2013 dry season, at the Institute for Agricultural Research (IAR) Farm, Samaru, in the northern Guinea savannah ecological zone of Nigeria to assess the performance of two extra-early maize varieties (SAMMAZ-28 and SAMMAZ-29) as influenced by rate of nitrogen and intra-row spacing. Treatments were laid out in a Randomized Complete Block Design (RCBD) replicated three times. Application of 90 kg N ha-1 gave significantly higher leaf area index, dry matter, net assimilation rate, flag leaf area, cob length, cob diameter, number of grains per cob and yield ha-1 than other levels (0, 45 and 135 kg N ha-1 ). Control treatment took statistically more number of days to attain 50% tasseling and silking than other levels. Spacing of 20 cm produced significantly higher yield, 100-grain weight, cob weight plant-1, ear leaf area, plant height, relative growth rate, crop growth rate and stand count than other spacing; the closest spacing (15 cm) produced significantly higher percent emergence, number of days to 50% tasseling and number of days to 50% silking, than the widest spacing. Varying spacing had no significant effect on plant height, flag leaf area, cob length, cob diameter, number of grains per cob, net assimilation rate and dry matter. There was positive and highly significant correlation between grain yield and dry matter, plant height, cob weight plant-1, cob length plant-1, cob diameter and 100-grain weight in both seasons. Regression analysis showed the optimum yield for SAMMAZ-28 to be 3437.6 kg ha-1 at 120 kg N ha-1 and 3989.4 kg ha-1 at 111 kg N ha-1 for wet and dry seasons, respectively; while for SAMMAZ-29 the optimum yield was 3521 k g ha-1 at 114 k g N ha-1 and 3385.56 kg ha-1 at 94 kg N ha-1 for wet and dry seasons, respectively. In conclusion, it could be suggested that SAMMAZ-28 with 111 kg N ha-1 in dry season and SAMMAZ-29 with 114 kg N ha-1 in wet season, each sown at 20 cm intra-row spacing could be used by farmers in the northern Guinea savannah ecological zone of Nigeria.