The biological reproductive aspects of the worm lizard, Diplometopon zarudnyi, in the Riyadh region of Saudi Arabia, were investigated over a period of 1year. Study of the reproductive cycles of male and female D. zarudnyi revealed that the breeding season is relatively short, since it extends from early April to late June. Thereafter, females lay the eggs during July, and hatching probably takes place during August. However, offspring were seen at mid-October. During this period (July–October), no evidence of sexual activity was observed; this may indicate just a single clutch during the year. Testis weight was increased ( ) during reproductive activity where maximal expansion of seminiferous tubules was also attained ( ) during May. On the other hand, the ovarian activity was the highest throughout April, May and June, when ovarian parameters were greater and each ovary was loaded with 6–9 eggs with an average egg diameter of 1.5mm. A positive correlation was recorded between the weight of fat bodies in the male and female lizards and their reproductive activity. Maximum weight of fat bodies was reached during May (  and  ).