Amino acid screening in an institute for children with hearing defects led to the detection of a 14 years male with histidinuria. Further investigations established the diagnosis histidinemia. In this normal intelligent patient audiologic tests showed bilateral internal ear hearing defect. It is accepted that the hearing defect is the reason for speech abnormities in form of diminished articulation. But it is not clear how far the inborn error of histidine metabolism is directly responsible for the hearing loss. This observation suggests that the well known speech defects in histidinemics are partly caused by hearing disability.