Field experiments were carried out at Sakha Agric. Res. Station, in 1999 season to evaluate the population density of aphids on nine maize cultivars (SC 10, SC 120, TWC310, TWC320, TWC321, TWC322, TWC323, TWC324, and Giza 2) and its relation to the yield.                 The obtained results revealed that aphid numbers were more on the terminal leaf than leaf of ear, bottom leaf and tassel for all the tested cultivars. Based on the general mean of aphids throughout the whole growing season Giza 2 was more susceptible to aphid infestation than the other cultivars, while SC10 was the least susceptible. Also, it can deduced that aphid number-yield loss relationship was not clear, since the highest yield loss was obtained in case of SC10 in spite of receiving the lowest number of aphids. On the other side, Giza 2 that exhibited the highest number of aphids recorded an increase in yield loss. But, in case of TWC320, 321, and 323, the increase in yield loss was correlated with the high number of aphids on the plant tassel. Both, SC120 and TWC310 cultivars approved to be the more tolerance cultivars to aphid infestation and recorded the lowest yield losses.