Two field experiments were carried out at Agricultural Research and Experimental Station, Faculty of Agriculture at Moshtohor, kalubia. Egypt, during 1984/85 and 1985/86 seasons, to study the effect of number of irrigation, N and p fertilization treatments on associated weeds grown with lentil. Each experiment included 24 treatments which were the combination of four irrigation treatments and six fertilizer treatments. Number of irrigation showed significant cf f.ct on fresh as well as dry weight of weeds/rn’ at different stages of growth in both seasons. The weight of weeds/rn’ significantly increased as the number of irrigations increased up to three times. Lentil fertilization with N and P significantly increa seed weeds density, expressed as fresh and dry weight in lentil plots, but the unfertilized treatments showed the lowest fresh and dry weight of weeds/a’. The effect of the interaction between number of irrigation and NP fertilizers was not significant on all studied, characters.