Angiotensin Converting enzyme (ACE or kininase II) converts angiotensin I to angiotensin II and inactives bradykinin. This enzyme exists in three isoforms: somatic form with two domains N and C-domain, ACE germinal and ACE N-domain detected in the body fluids. Our group have described  three isoform of ACE: 65, 90 and 190 kDa. Where  the 90 kDa was described  as a possible genetic marker of hypertension. In the present study we verified the relationship between expression and synthesis of ACE isoforms especially of the 90 kDa,  with malnutrition during childhood. Malnourished children (MC) were studied (height-for-age or weight-for-age Z-score < -1) aged 2-8 years and a group of children, normal controls (NC), with Z-score between 0 and 2 same aged and recruited from the same region. The urines were concentrated and dialyzed using 50 mmol/L tris-HCl, pH 8,0 and their ACE catalytic activity was measured fluorometrically with Hipuryl-His-Leu (HHL) and ZPheHL as substrates and ACE expression was detected by Western Blotting. After analysed the blood pressure (BP) measuraments we infer that the prevalence of hypertension in the group MC is very high (43%). However 36% present high BP having a risk to develop hypertention, almost 57% of this group are normotensive. Among the NC 47% of the children are normotensive, 22% have normal BP with the tendency to become higher and 31% are hypertensive. The enzymatic activity measured using ZPheHL is higher than the one measured using HHL in both groups. However when we analized the ratio ZPheHL/HHL between both groups, we verified that this ratio is higher in just 6 to 8 year-old children where the NC ratio is lower (1.1) than the MC (1.4). In the subgroups of  2 to 4, and 4 to 5 years is found a bigger difference between the ratios (1.2 and 2.0 in group with nutrition problems and 4.4 and 3.1 in the NC respectively). The expression of ACE shows within MC that 13 subjects present the 3 isoforms of ACE, 11 present 90 kDa and 65 kDa and just 1 presents a 65 kDa isoform. In the NC we found 18 children with 3 isoform, 2 present 90 and 65 kDa and 1 with 65 kDa isoform. Our suggestion is that in the urine samples from children ranged from 6 to 8 years, the ACE N-Domain that is responsable for inactivation of the Ang 1-7 which is an antagonist of AII,could be directly releated with hypertension in this children.