The insect fauna of the native milkweed plant Calotropis procera (Ait.) Ait. in the Ibex Reserve, in the Central Region of the Kingdom of Saudi Arabia was studied. Insects were sampled bimonthly from May 2007 to late April 2008, and then irregularly until June 2011. Ninety-nine insect species belonging to eight orders, 43 families and 80 genera were found to have some type of association with the plant during the period of sampling. The carpenter moth, Semitocossus Johannes (Staudinger), scale insect Contigaspis zilla (Hall) and milkweed aphid Aphis nerii (Boyer de Fonscolombe) were pests attacking the plant. Nine taxa collected represent new country records for Saudi Arabia: Clambus sp. (Coleoptera, Clambidae); Angiometopa sp. (Diptera, Sarcophagidae); Steleoneura sp. (Diptera: Tachinidae); Goniurellia longicauda Freidberg (Diptera, Tephritidae); P silochalcis sp. (Hymenoptera, Chalcididae); Odynerus blanchardianus Saussure (Hymenoptera, Chrysididae); Nomioides kenyensis Pesenko & Pauly (Hymenoptera, Halictidae); Cremastus aegyptiacus Szepligeti (Hymenoptera, Ichneumonidae) and Cerceris chlorotica Spinola (Hymenoptera, Sphecidae).