OBJECTIVE This study examined the clinical effects of nitrous oxide conscious sedation on children. METHODS Fifty-nine healthy children (ages 4 to 13, mean age=7.7 yrs.) requiring dental restorative treatment with nitrous oxide sedation were studied. The behavior and clinical effects were assessed before and 5 minutes after 50% nitrous oxide sedation. In addition, the children were instructed to draw 4 selected figures from the Bender Visual Motor Gestalt Test to evaluate psychomotor performance and report on their perceived feelings with nitrous oxide. The total sample was divided into various groups for analysis by age, gender, and prior nitrous oxide experience. RESULTS The most common effects of nitrous oxide sedation were open hands (90%), limp legs (81%), and facial smile (66%). Almost all of the children (95%) liked the nitrous oxide, and 86% reported feeling different. In the measure of psychomotor performance, 75% of the children had 2 or less errors initially and 5 or less errors with nitrous oxide. CONCLUSIONS There are observable signs and perceived symptoms of nitrous oxide conscious sedation in children. In addition, nitrous oxide at a concentration of 50% has a small but significant effect on the psychomotor ability of children.