목적: In children, even though real ear measurement (REM) is a crucial process of hearing aid (HA) verification, due to cooperation issue, it is technically difficult to perform in some cases. To evaluate the success rate of REM and to find any predictors of REM failure for children under age of 6. 방법:Design: A retrospective study. Study samples: Single-centered 41 children under age of 6 were included in a 5-year period retrospectively. Main audiological measurements were 4 frequency auditory steady state response (ASSR4), auditory brainstem responses(ABR) threshold and type of hearing loss. Methods: REM was tried on 3 step manner. First trial was during awake, if fails, either chance of next trial for natural sleep of nap time or drug induced sleep of the next audiological test. 결과:Among the 41(17 boys, age 28.9 ± 23.8 months) children, over all REM success rate was 87.8 %. 17 of trial during awake, 5 of natural sleep, 14 of drug induced sleep have succeeded. Neither 1 awake nor 4 drug induced sleep had succeeded REM. Comparing the age under 3 between over 3, did not differ in success rate (p> 0.05). REM success rate between trial during awake, of natural sleep, and of drug induced sleep did not differ in success rate (p=0.113). There were no predictors of REM failure clinically available. 결론:Feasibility of REM for hearing aid fitting in children aged under 6 years might reach near 90% if we use 3 step manner. Our findings suggest the importance of multiple trial of REM during the HA fitting in children under age of 6.