The data of pediatric patients who required sedation for non-invasive examinations, aged 1 day-13 yr, were retrospectively collected from December 2019 to June 2020.They are divided into 4 groups according to age: newborn (age 0-28 days) group, infant (age 29 day-1 yr) group, toddler (age 1-3 yr) group, and child (age 4-13 yr) group.Chloral hydrate 50 mg/kg was administrated orally.When the Ramsay score was ≤ 4 points at 30 min after administration, oral chloral hydrate 25 mg/kg or intranasal midazolam 0.1 mg/kg or intranasal dexmedetomidine 1 μg/kg was given as rescue administration.If the Ramsay score was still ≤ 4 points at 30 min after rescue administration, the examination was rescheduled or rescue drugs were given again by the anesthesiologists according to the condition and the urgency of the examination, with the number of administration not exceeding 3 times.The sedation failure was defined that the patients could not complete the diagnostic procedures after administration due to various reasons (including severe respiratory depression, rescheduled examination, parents' refusal to rescue administration, and Ramsay score still ≤ 4 points after 3 times of administration). The success of sedation at first attempt, success of rescue sedation and success of total sedation were recorded.The occurrence of sedation-related adverse events such as coughing, vomiting, allergies and respiratory depression was recorded.Compared with neonate group, the success rate of sedation at first attempt and success rate of total sedation were significantly increased, the incidence of sedation-related adverse events was decreased in infant, toddler and child groups ( P<0.01). There was no significant difference in the parameters mentioned above among infant group, toddler group and child group ( P>0.05). In conclusion, the efficacy of chloral hydrate for sedation is not good when used in neonates undergoing non-invasive diagnostic procedures.