In order to determine the relationship between yield and some morphological and physiological traits, as well as important traits that affect grain yield in bread wheat, a field experiment was conducted at Cereal Research Farm, Seed and Plant Improvement Institue, KaraJ in 2007. Three hundred and thirty five bread wheat recombinant inbred lines were evaluated in an Alpha Lattice design with two replications. Grain yield was positively correlated with all of the yield components, but was negatively correlated with days to heading, days to anthesis, days to ripening, extrusion peduncle length and second internode length. In stepwise regression, grain production rate was the first variable entered in the model and explained a higher percentage variation in grain yield. Path analysis showed that grain production rate and biological yield (0.534 & 0.532) exerted the most direct effects on grain yield. On the basis of these result, it is suggested that criteria such as number of spike per m2, number of grain per m2, seed weight per spike, biological yield production rate , grain production rate and biological yield could be considered as effective criteria for selecting towards grain yield improvement in bread wheat.