Objective: Field experiment was conducted in 2009 to investigate the effects of plant density and weed interference on morphological characteristics and yield of corn (Zea Mays, L.) at Research Station of University of Tabriz, Tabriz, Iran. Methods: The experiment was arranged as split plot based on randomized complete block design with three replications. Plant density (D1, D2, D3 and D4: 5, 7, 10 and 16 plant m-2, respectively) were assigned to main plots and three levels of weed interference ((W1, W2 and W3: weed free, between row weed interference and full-season weed interference) were allocated to the sub plots. Results: The Results showed that with increasing plant density, grain and biological yield increased, but cob weight, ear length, ear diameter and harvest index decreased. The highest amount of morphological traits and harvest index was obtained from 5 plant m-2.The weed interference treatments had significant effects on above traits so the highest morphological traits, grain yield, biological yield and harvest index was obtained from weed free treatment. These results indicated that high plant densities because of decreasing weed interference and increasing grain and biological yield, is the effective agronomic solution for increasing corn performance in the field and can be used to reduce consumption of chemical pesticides in sustainable agriculture systems.