Anopheles maculipennis Meigen is the chief of sole malaria carrier in the Caucasus and in northern Iran. The susceptibility level of adult female An. maculipennis to insecticides was studied in field surveys, in different localities of Iran, during 1970-77. Tests were carried out in localities where the application of DDT for malaria control has been withdrawn since 1968. The studies showed that An. maculipennis is resistant to DDT but susceptible to dieldrin and malathion in Iran.