The purpose of this study was to identify the risk factors associated with low peripheral oxygen saturation (SpO 2 ) and delayed recovery of dental patients with disabilities after intravenous sedation. A total of 1213 patients with disabilities were retrospectively investigated with respect to demographic parameters and sedation conditions. Multivariate logistic analyses were conducted for patients with an SpO 2 ,90% and a recovery period of .60 minutes to identify the risk factors for poor sedation conditions. A significant odds ratio related to decreased SpO 2 was observed for age, sex, midazolam and propofol levels, concurrent use of nitrous oxide, cerebral palsy, Down syndrome, and mental retardation. The most problematic patients were those diagnosed with Down syndrome (odds ratio, 3.003-7.978; 95% confidence interval; P , .001). Decision tree analysis showed an increased risk of decreased SpO 2 in males with Down syndrome or after administration of .0.493 mg/kg propofol in combination with midazolam. An increased risk of delayed awakening was seen in patients aged less than 21 years and in males administered .0.032 mg/kg of midazolam. Intravenous sedation for dental patients with disabilities, particularly those with cerebral palsy, Down syndrome, or mental retardation, increases the risk of decreased SpO 2 . In addition, delayed recovery is expected after midazolam administration.