This study sought to determine the point incidence of middle ear pathologic conditions and to ascertain the value of acoustic impedance-admittance measurements in detecting otitic pathologic conditions in young children with Down's syndrome. Pneumo-otoscopy and acoustic impedance measures were performed on 38 children (mean age, 3.1 years) with Down's syndrome. Results indicated that more than 60% of the series demonstrated otoscopic and acoustic impedance evidence of middle ear effusion, which is in keeping with results reported previously for older children and young adults with Down's syndrome. Of particular interest was the large number of normal ears that displayed absent crossed and uncrossed acoustic reflexes,which suggested that measurement of the acoustic reflex may be an unreliable parameter for confirming the presence of middle ear effusion in children with Down's syndrome. To maximize the educational potential of these children, a careful examination to detect middle ear effusion must be performed at periodic intervals. If persistent effusion is detected, appropriate surgical management should be instituted without delay.