residual activity and persistence of deltamethrin on different surfaces against Sitophilus oryzae (L.) and Rhizopertha dominica (F.) adults was investigated. Three rates of deltamethrin (0.4, 0.3 and 0.2 mg A.I /cm2) was applied to steel, ceramic tile, plywood and cement (wall or floor surfaces) and plastic, damour, polypropylene and jute (fabric surfaces). Adults were released on surfaces after 24 hrs. from application (0 time) then after oneweek interval during 6 months. The adult mortality percentages were recorded after 24hrs. from exposure. Results indicated that: - The residual activity of deltamethrin against the two tested insect species adults was concentration, surface and time after application –dependent . -Adults of S.oryzae adults were more susceptible than R. domonica with all detamethrin concentrations on different surfaces in all period intervals. - Steel and ceramic surfaces with all concentrations of deltamethrin gave greatest residual activity with complete mortality for 6 months against the two insect species. - Also, the residual effect of insecticide was high on plastic, polyethylene surfaces, followed with plywood and damour surfaces. - Deltamethrin with cement surface deteriorated rapidly starting from the initial time and failed to give 100% kill to the two tested insect species. - Also, values of gross persistence indicated that, non-porous surfaces ( steel ,ceramic, plastic and polyethylene ) were the most ideal to retain deltamethrin efficacy compared with the other porous surfaces.