 Clinical, randomized and controlled trial, conducted in a pediatric surgery ward of a university hospital in São Paulo. Data collection occurred from February 26th, 2007 to July 07th, 2008, after ethical merits of research approval. The sample comprised 382 venous puncture randomly allocated in the experimental group EG, venous puncture guided by VUS, or in the control group CG, traditional method of venous puncture. Variables related to children, intravenous therapy and professional characterization were collected. The dependent variables included the obtainment of peripheral venous access, the assertiveness, the catheter dwell time and the occurrence of local complications. For the statistical analysis were applied the Pearson Chi-square, Fishers Exact, Generalization of Fishers exact, Mann-Whitney, Likelihood Ratio and Prevalence Ratio significance level of 5. 