The objective of the study was to determine important agronomic traits of sweet corn hybrids under weeds fully controlled and not-controlled conditions at different plant densities. The study was carried out in Hajiabad, Hormozgan, Iran in 2006. It was a split-split plot design based on a randomized complete block design with four replications. The main plots included sweet corn hybrids, namely KSC403 and Shimmer, the sub-plots included two levels, namely weeds fully controlled and not-controlled conditions, and the sub-sub-plots included three densities of 53000, 67000 and 89000 plants/ha. The results of analysis of variance showed that the variations of Shimmer and KSC403 in grain yield, 100-grain weight, grain number/row and row number/ear were significant. Also, weeds full control increased the grain yield by 7.8%. The highest grain yield was 9700 kg/ha for Shimmer at the density of 89000 plants/ha under weeds fully controlled conditions. In total, Shimmer exhibited superior traits over KSC403. In addition, Shimmer produced the highest grain yield at the density of 89000 plants/ha under weeds fully controlled conditions.