Monitor lizards are lizards in the genus Varanus, and they are widespread in Africa, Asia, Australia and the Pacific islands. They are primarily carnivorous, with frugivorous exceptions, and are active during the day due to their heliothermic nature. They are endangered due to habitat loss, hunting and due to invasive species. Adequate determination of the sex of monitor lizards is important both for the purpose of conservation and for the establishment of breeding colonies, as well as in private breeding for the trade of exotic pets. Gender can be determined by a number of techniques, and in this paper, the technique of survey radiography of ossified hemibaculum was investigated. Determining the sex of adult monitor lizards using the rendgenography technique proved to be very reliable in adults due to the ossification of the paired hemibaculums. In this work, 21 individuals from 7 different species were recorded. In most species, adult males show paired hemibaculums with one phalang, while in V. salvadorii two phalanges are present on each hemibaculum. This technique has advantages over some other sexing techniques due to the avoidance of mechanical injuries and additional stress to the animals, as well as the possibility of reducing animal manipulation. An additional advantage of this technique is the possibility of detecting additional pathologies while screening the animal.