Systemic lupus erythematosus is a chronic multisystemic autoimmuneinflammatory disease, polygenic inheritance and many environmental factors playa role in its development. ACE gene insertion / deletion ( I/D) polymorphismwithin intron 16 has been shown to encode the ACE enzyme which is responsiblefor the different clinical manifestations of SLE. This study was conducted on 50 SLE patients diagnosed according to theACR criteria and 29 apparently healthy volunteers as control group , all subjectswere subjected to full history taking, clinical examination , Radiological andlaboratory investigation (CBC, ESR serum urea and creatinine 24 hours urinaryprotein) and genetic study of the ACE gene I/D using the PCR method. The frequency of DD genotype was statistically significantly increased in SLEpatients compared to control group , p = 0,009, and also the DD genotype wasassociated with higher serum ACE level when compared to DI and II genotypesOn comparing the frequency of DD and DI genotypes between SLE patients withand without vasculitis and those with and without nephritis, a statisticallysignificant increase was observed in DD genotype. The associations observed in the current work highlight the potentiallyimportant role of ACE genotype and subsequently serum ACE in thepathophysiology of SLE.