This study compared the sedative effectiveness of orally administered ketamine to a combination of oral meperidine/promethazine (Demerol/Phenergan) in two groups of children. One group received ketamine at a dose of 6 mg/kg and the other group received meperidine/promethazine combination at a dose of 2 mg/kg and 0.5 mg/kg, respectively. All children received nitrous oxide 30-50% titrated to effect. A four-point modification of the Houpt et al. rating scale for the overall behavior was used in the evaluations. The quality of sedation, as rated by subjective measurement of overall behavior (sleep, crying, body movement), was higher in the ketamine group (borderline significance; P = 0.07). Mean onset time was significantly shorter (P < 0.001) for ketamine (20.5 min) than meperidine/promethazine (42.4 min) and postoperative sleep time (recovery) was also shorter (borderline significance; P = 0.08) for ketamine (55.6 min) than meperidine/promethazine (106.8 min). Operative times were similar, but the placement of rubber dam and local anesthetic were slightly better tolerated in the ketamine group. Vomiting was significantly more prevalent (P = 0.05) among those who received oral ketamine. Vital signs were consistent for the two groups with no oxygen desaturation below 95%.