The residual life of bendiocarb was evaluated under field conditions in southern Mozambique. Bioassays conducted at monthly intervals using susceptible Anopheles arabiensis demonstrated that bendiocarb had an effective residual life of 6 mo. The different types of surfaces sprayed did not affect the residual life of bendiocarb. Therefore, to achieve effective control in a malaria-endemic area such as southern Mozambique, two spray rounds per annum are necessary.