Population densities of A.gossypii Glover on five common tomato cultivars,including the two varieties Strain B.V. 14S and Cale Ace varie‌ties and the three hybrids UC 97-3, Petro Pride and Madear, were esti‌mated at the two successive early summer seasons of 1996 and 1997 at Demietta Goverorate (northern part of Nile Delta). Alatae and both apterous and nymphs mean numbers of aphid in-dividuals were determined along with its vertical normal distribution on upper, middle and lower plant parts. Susceptibility of the above men‌tioned tomato cultivars were also studied. Differences between mean numbers of A.gossypii Glover indived‌uals, alatae and both apterous and nymphes/10 leaves, were significant during both seasons. One peak of aphid population was recorded on 18th and 21st May of the two studied seasons on the five tomato culti‌vars. Alatae and unwinged (apterous and nymphs) forms induced one peak of the population coincident to that recorded in the individual pop‌ulation. The higher percentage of both apterous forms and nympes were obtained on the low susceptible tomato cultivars, in the opposite of a high percentage of alatae population on the most susceptible cultivars. Otherwise, lower leaves of the tested tomato cultivars harboured the highest mean numbers of aphid individuals followed by the middle ones, then the upper ones. On the other hand, differences of the mean numbers of aphid in-dividuals/10 leaves of the tested tomato varieties and hybrids were sig‌nificant, during the two successive seasons. Tomato strains B.V.F. 145 variety and UC 97-3 hybid were the least susceptible, while Peto Pride hybrid was moderately suscepitble, and the two cultivars of Cale Ace and Madear were the most suscepitble.