Gamma radiation-induced translocations and inversions in Anopheles culicifacies Giles involving all 3 chromosomes have been isolated and examined cytologically in both the mitotic and polytene chromosomes. These aberrations support the hypothesis that only the short arm of the mitotic X chromosome is present in the polytene chromosome complement, and that 2R and 2L and 3R and 3L of the polytene chromosomes are correlated with the longer sub-metacentric and metacentric mitotic chromosomes respectively. A homozygous pericentric inversion involving most of the long arm of the mitotic X chromosomes has been isolated. Individuals homozygous for an autosomal-autosomal translocation have been recovered, but a pure breeding homozygous line has not been established. There is no evidence for crossing over between the X and Y chromosomes.