Background: The common house mosquito, Culex pipiens, is abundant in Egypt and act as a vector of pathogens of medical and veterinary importance. Aim: The present study aimed to compare the toxic effect of rose bengal a photosensitizer to that of chlorpyrifos, a commercially available larvicide against the early 3rd larval instar of Cx. pipiens. Methods: We compare the toxic effect of rose Bengal exposed to sunlight from 10 am to 4 pm to that of chlorpyrifos, against the early 3rd larval instar of Cx. pipiens. Results: Treatments revealed dose-dependent mortality, reaching 100% after treatment with rose bengal for 6 hrs and 90.6% for chlorpyrifos for 24 hrs. Six hours post-treatments, the LC50 of rose bengal and chlorpyrifos were 4.9x10-6 and 4.9x10-4, respectively; while the LC95 were 2.0x10-3 and 4.0x0-3, respectively. Based on the LC50 values of chlorpyrifos as a reference substance, rose bengal was found 100 times more potent than chlorpyrifos. The LT50 of rose bengal ranged from 34.8 to 1.1 hrs post-treatment with1×10-6 M and 1×10-2, respectively. The LT50 values of chlorpyrifos ranged from 3065.9 to 6.1 hrs after subjecting to 1×10-4 M and 1×10-3, respectively. Conclusion: It could be concluded that rose bengal could be used to prevent mosquito bites and their associated diseases as an alternative to traditional insecticides and an eco-friendly larvicide.