The aim of this study was to investigate the association among C-reactive protein, homocysteine plasma levels and urinary nitric oxide with endothelial dysfunction in healthy subjects with or without family history of hypertension and the detection of the 90 kDa ACE isoform in their urine, an isoform considered a possible marker for high blood pressure. Thirty-one healthy male subjects, age ranging from 18 to 40 years took part in this study. They were evaluated by brachial Doppler US to test the response to reactive hyperemia (endothelial function-ED) and also underwent a panel of blood tests for determination of C-Reactive Protein (CRP), homocysteine plasma levels (HCY) and urinary nitric oxide (NOu). They were initially divided into groups according to the presence (+) or absence (-) of the 90 kDa ACE and the presence (F+) or absence (F-) of family history of high blood pressure. Therefore we had initially two groups: F+/90+ (n=26) and F-/90- (n=5). There was a trend to an impaired endothelial function (12.02±5.2% vs. 16.38±7.5% p = 0.07) in F+/90+ and F-/90- groups respectively. Regarding inflammatory marker, HCY, and NOu we did not detect any significant difference between groups. When we analyzed these subjects dividing in 3 groups (H+/90+ (n=16), H-/90+ (n= 6) and H-/90- (n= 5)) we also found a trend for an impaired endothelial dilation in subjects who presented the 90kDa isoform as follow: 11.8% in H+/90+ group, 8.15% in H-/90+ and 14.6% in H-90- group (p = 0.065). HCY levels were also marginally lower in H+/90+ than in H-/90+ and H-/90-, as follow: 10.7±1.9 vs. 11.5±3.5 and 14.3±3.8, p = 0.055, respectively. Considering the results obtained when we divided in 3 groups, our data suggest that the presence of the 90 kDa ACE itself may have a negative impact in flow mediated dilation stimulated by reactive hyperemia. A same trend was observed in HCY plasma levels but not in CRP. NOu showed a large variation which did not allow any analysis at this point.  Supported by FAPESP.