A field study was conducted at the Agricultural Research Farm of Razi University, Kermanshah, Iran to investigate the effects of phosphate biofertilizer, row spacing and plant density on corn yield and weed growth. The experiment was a factorial with three factors arranged in a randomized complete block design with three replications. The first factor was phosphate biofertilizer (inoculation and non-inoculation), the second was row spacing (conventional (75 cm) and reduced (50 cm)) and the third was plant density (66,666 plants·ha -1 (conventional plant density) 83,333 and 99,999 plants·ha -1 (1.25 and 1.5 times the conventional plant density, respectively)). Results indicated that corn yield and weed growth were significantly influenced by row spacing and plant density. So that, corn yield improved and weed biomass diminished in response to increasing plant density and decreasing row spacing. However, phosphate biofertilizer had no significant effect on corn yield, whereas, weed biomass was notably increased when phosphate biofertilizer was applied. Overall, this study revealed that both yield and weed control in corn field can be improved by alteration of the planting arrangement.