The influence of five exotic cotton (Gossypium spp.) cytoplasms on yield, yield components, fiber properties, and insect populations was determined at Stoneville, Miss. The five cytoplasms were G. herbaceum L., G. arboreum L., G. anomalum Wawra ex Wawra & Peyr., G. barbadense L., and G. tomentosum Nutt. ex Seem. The five cytoplasms were combined by repeated backcrossing into the following upland cotton (G. hirsutum L.) cultivars: ‘B3080’, ‘Coker 201’, ‘Delcot 277’, ‘Deltapine 16’, and ‘Stoneville 213’. The average number of backcrosses into G. hirsutum was 10.1 and into the specific cultivars, 6.5.The characteristic most influenced by exotic cytoplasms was yield. Cytoplasm from G. arboreum decreased yield I8%, averaged for all cultivars. Exotic cytoplasms in general decreased yields, but this trend was not consistent for all cultivars. The average 1977 decrease in yield was 80, 61, 41, 17, and −5 kg/ha for Deltapine 16, Coker 201, Stoneville 213, B3080 and Delcot 277, respectively. The foreign cytoplasms had no strong deleterious effects on yield components and fiber properties.No evidence of variations in tolerance to tarnished plant bugs (Lygus lineolaris Palisot de Beauvois) was detected in the 1977 study. In 1978 no differences due to cytoplasms were detected in numbers of tarnished plant bugs and white flies (Trialeurodes abutilonea Haldeman). However, the AD3 (G. tomentosum) cytoplasm resulted in a 70% increase in numbers of leafhoppers (primarily Empoasca spp.) and a 35% decrease in weights of 7‐day old larvae of tobacco budworm (Heliothis virescens F.).The interaction of some nuclear genes and exotic cytoplasms was compatible for yield and significant for some pest damage. This result suggests that a back‐up cytoplasmic system could be developed to help reduce the danger of major ephiphytoties or damage by insects.