Increased cardiovascular and renal disease has been described in humans with intrauterine or early life undernutrition. Microalbuminuria (MA) is a marker of renal and endothelial dysfunction, and a predictor of cardiovascular and renal disease. We hypothesized that undernourished children have increased MA, and after nutritional recovery, the MA concentrations would decrease to normal values. We evaluated the concentration of MA in three groups of children (mean age: 10.75 ± 2.45; range: 5.62 to 15.94): treated in a day-hospital and recovered from previous undernutrition (R group (n=32) height/age (HAZ) (mean±SD) -0.58 ± 0.68, BMI/age (BAZ) -0.46 ± 0.74); undernourished group (U group (n=48); HAZ -1.40 ± 1.10; BAZ -1.76 ± 1.06) and control group (C group (n=50); HAZ -0.37 ± 0.91; BAZ -0.27 ± 0.86). All families of participants signed the Free and Informed Consent form. The study was approved by Research Ethics Committee of the Federal University of São Paulo (number 1302/09). Children underwent preliminary tests to detect urinary infection, anemia and thyroid axis alterations. Those with positive results were treated and afterwards included in the study; and if not possible, excluded. A morning spot urine sample was collected by the mother after waking up of the child. The mothers were instructed at least in two occasions about the procedure and reminded by phone call the day before the collection. Albuminuria was measured by an immunoturbidimetric assay and the results were expressed as the ratio of urinary albumin/creatinine (mg/g). The U group showed lower anthropometric values than the other two groups (HAZ: U= -1.4 ± 1.1, C= -0.37 ± 0.91 and R= -0.58 ± 0.68; BAZ: U=-1.76 ± 1.06, C=-0.27 ± 0.86 R= -0.46 ± 0.74, both ANOVA p<0.001); and greater mean values of MA than the R and the C groups (U= 10.4 ± 16.1 mg/g, C= 6.3 ± 8.2 mg/g and R= 4.6 ± 4.3 mg/g, p=0.040, ANOVA). Eight percent of the U group showed MA (defined as > 20 mg/g). None of controls had MA. When evaluating the difference in prevalence between the type of undernutrition (stunting or underweight), 12.5% of children with stunting had MA, while the underweight group had 4.2%, while the R group had a prevalence of 6.3%. Using a MA lower cutoff > 10 mg/g was used to identify children at risk, we found that 16.7% of the R group, 31.2% of the U group and 8.5% of C group showed elevated albuminuria (Pearson chi-square = 0.018). Our results showed the presence of microalbuminuria in undernourished children which may be a marker of higher risk for cardiovascular and renal disease in future life. On the other hand, after treatment for undernutrition, recovered children showed results similar to controls.