Katz (1978) has suggested that mild, fluctuating conductive hearing loss due to middle-ear anomalies may account for the language and attention problems of learning-disabled children. His position was extended here to include autism. Normal, learning-disabled, and autistic children received repeated impedance measures over 5 weeks. A repeated-measures ANOVA of central tendency and variability values led to the conclusions that (1) fluctuating, negative middle-ear pressure greater than normal characterizes both autistic and learning-disabled children, (2) the negative pressure is greater in autistic than in learning-disabled children, and (3) the condition is typically bilateral for autistic children.