Randomized, double-blind, placebo controlled study conducted at the Clinical Hospital of Porto Alegre between November / 15 and August / 16. This study was approved by the Ethics Committee of the Institution. Participated children requiring venipuncture randomized in the intervention group who received the ketamine IN 4 mg/kg and placebo saline group. The groups were compared: Puncture time, ease the nurse to perform the procedure, adverse events, changes in vital signs and perception of the companion.