The study was carried out on 13 children (2-12 years) subjected to abdominal aortography. The children were divided into 2 groups. Changes in plasma concentrations of ketamine and its metabolism were evaluated during anesthesia after bolus injection of ionic highly osmolar and nonionic low-osmolar x-ray contrast agents (RCA). Injection of an RCA bolus was associated with a 2-fold more rapid drop of the anesthetic concentration in the blood, increase of renal clearance of ketamine and its metabolites; the osmotic effect of ionic highly osmolar and nonionic low-osmolar RCA on ketamine pharmacokinetics virtually did not differ.