Population density of the tomato fruit worm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) and estimating its rates of infestation in tomato fields at Thomas district, Lake Nasser region, Aswan Governorate, Egypt was studied. Estimation of the infestation rates using direct counts of the pest larvae and number of moths per pheromone trap was undertaken for two successive growing seasons 2006/07 and 2007/08. Highest rates of H. armigera infestation ranged between 20.8 and 21.3% in the first season and between 9.4 – 17.9% in the second season were recorded during the period extended from first week of February to mid-March, respectively. General seasonal means of infestation rate were 9.6 and 11.2% in seasons 2006/07 and 2007/08, respectively. General seasonal mean number of moths/trap was 9.8 and 7.5 moths /trap during the first and second seasons, respectively. Statistical analysis showed that there was a positive correlation between the rates of infestation and the number of trap catches in both seasons.