Abstract: Two field experiments were carried out in the experimental farm of Rice Research and Training Center (RRTC), Sakha-Kafr-El Sheikh, Egypt during two summer seasons of 2009 and 2010. The aimed of the study is to investigate the effects of some allelopathic genotypes of rice, transplanting spaces and weed control treatments on weed characters, yield and its components. A strip split plot design with three replicates was used. The most important findings of this study could be summarized as follow: Regarding rice genotypes, both of Gz 7955 and Gz 8565 lines not only achieved the lowest values in weeds fresh and dry weights (g m-2) but also recorded the high yield and its attribute in the two seasons. Transplanting spaces varied in biomass, the closer space recorded the significantly lower weed character which subsequent gave higher grain yield. The full dose of penoxsulam 24% sc (35 mL fed-1) ranked as the best weed control treatment in reducing all weed characters and increasing rice yield followed by herbicidal application at half dose as compared to weedy check that recorded the highest weeds traits and the lowest rice yield characters.