Sexing is very easy for T. jacksonii because they develop sexually dimorphic traits shortly after birth.

Male Jackson’s chameleons have three horns, and the adults are generally larger than females.

Female Jackson’s chameleons have no horns or just one diminished horn, and are generally smaller. Occasionally females will have 3 horns, but all will be must smaller than a male’s.

Differences between sexes in T. j. xantholophus. Contributed by Petr Necas.