The angiotensin-converting enzyme (ACE) gene in humans contains an insertion-deletion polymorphism in its intron 16. Because of its involvement with the renin-angiotensin system, the insertion-deletion polymorphism of the ACE gene has been widely investigated in different populations and in case-control studies. However, similar studies for Arab populations are limited in number. Therefore we have investigated the frequencies of the *I and *D alleles of the ACE gene among Sudanese, Somalis, and Arab nationals of the United Arab Emirates and Oman using previously described methods. Our data indicate a preponderance of the *D allele among the Arab and African populations studied (Sudanese, 0.64; Somalis, 0.73; Emiratis, 0.61; and Omanis, 0.71).