Nitrogen fertilization in grain sorghum significantly increases the amount of dry mass accumulated before flowering and at maturity. The highest dry mass translocation and contribution of pre-anthesis assimilations of the grain were observed at a moderate nitrogen rate of 120 kg N.ha-1. However, higher nitrogen rates (180, 240, 300 kg N.ha-1) reduced the efficiency of dry mass translocation and the contribution of pre-anthesis assimilations. Overall, nitrogen had a strong negative correlation with these factors.