In 2008, two transgenic rootworm resistant (RW) hybrids along with their near-isogenic (non-RW) hybrids were evaluated at Champaign, IL. These hybrids were grown under five levels of fertilizer N availability ranging from 0 kg ha-1 – 270 kg ha-1. Averaged across N rates, the RW hybrids produced approximately 1.4 Mg ha-1 more grain relative to their near-isogenic counterparts. Rootworm pressure in 2008 was generally low; root node injury scores for the hybrids were approximately 0.10 (Iowa State University 0-3 rating scale). The remarkable yield improvements along with apparently minor rootworm feeding suggest that even slight root damage can have a profound influence on grain yield. Harvest indices for non-RW and RW hybrids were equivalent indicating that increased grain yields resulted from greater total biomass accumulation. Averaged across N rates, RW hybrids increased total biomass accumulation at R6 by approximately 10% relative to their near-isogenic counterparts. There was a marked improvement in fertilizer N use efficiency from the RW trait in both hybrid pairs that was primarily a result of an improvement in N uptake efficiency which averaged 55% in non-RW hybrids and 71% in RW hybrids. Although the RW trait protected grain yield at all levels of N fertilizer, the N rate needed for maximum grain yield was not necessarily lower than that needed for non-RW hybrids suggesting that rootworm protected hybrids protect the investment in N fertilizer but might not reduce its use.