Objectives: The aim of this study was to assess central auditory processing (CAP) tests in patients with single sided deafness (SSD)and to study the effect of central auditory processing disorders(CAPD) on the contralateral routing of signal (CROS) hearing aid performance in these subjects. Design: This case-control study was performed in Audiovestibular unit, ENT Department. The study included 20 children with SSD and 20 healthy control children. All participants were sub- jected to CAP tests including pitch pattern sequence (PPS), gap in noise (GIN) and speech intelli- gibility in noise (SPIN) tests. The child was fitted with CROS and evaluated by SPIN test and bern benefit in single - sided deafness (BBSS) questionnaire. Results: There were lower SPIN, PPS, and GIN total correct scores in children with SSD than the control group. The group with normal central test battery has higher SPIN score and significant performance with questionnaire when fitted with CROS. Conclusions: Children with normal central auditory processing test battery performed better when fitted with CROS than those with abnormal test battery.