The eggs are oval, with a parchment shell, and they hatch the following April. They reach sexual maturity at anpit 5 years. Young are dark in color with red circles all over the body, and vertical bands of black and yellowish green on the neck. These neck markings disappear with age, but the red circles remain on the grey-brown bodies of adults. There is no precise information on brooding time in the wild.
Sexual maturity seems to be reached in the third to fifth year of life.
There are some reports, however, describing the monitors reproduction in captivity. The survivors were sent to the Basel zoo. In San Diego, six Cape monitors hatched after 170 to 176 days, and four of them grew up. In Wilhelma a female Merten's monitor laid thirteen eggs on 6 January 1965, eight of which were fertile. Six young hatched after 182 to 216 days.