The seasonal abundance and population dynamics of adult mosquitoe, Aedes aegypti, the main vector of dengue fever in Jeddah governorate was studied during the period of January to December 2007 using Black-Hole light traps. The study showed that Ae. aegypti was present throughout the year, but at significant different densities depending on the prevailing climatic conditions. Two peaks of adult activity were recorded. A pronounced peak was reported in September and another small one was in June. The larvicidal activity of five compounds against Ae. aegypti was evaluated. Taking LC50 values (concentration which to kill 50٪of mosquito larvae) into consideration, mosquito larvae of Ae. aegypti proved to be more susceptible to Pesguard FG 161 (0.046 ppm) than Actikil 50٪ (0.061 ppm) and Bacilod (0.142 ppm), respectively. The results indicated that Pesguard FG 161 was more effective against Ae. aegypti larvae than Actikil 50٪and Bacilod by about 1.3 and 3.1 times, respectively. On the other hand, the results showed that treatments with the chitin synthesis inhibitors Dudim 4%G and plant extract Neem oil against mosquito larvae of Ae. aegypti produced various biological effects on immature stages and adults. Therefore, in this study, cumulative mortalities during larval development to pupae and adults were taken as a criterion for evaluating the efficacy of Dudim 4%G and Neem oil. According to IC50 (concentration which inhibits the emergence of 50٪of mosquito adults), the compound Dudim 4%G (0.0003 ppm) was more effective against the Ae. aegypti than Neem oil (66.36 ppm).