Instructional supervision is a component of general supervision which educational supervisors carry out in learning institutions. Its’ primary function is the improvement of instruction aimed at enhancing teaching and learning. The study sought to find out the academic and professional qualifications & training of such supervisions, the extent of their involvement in carrying out supervisory activities, whether their frequency and methods of carrying out clinical supervision were adequate,their attendance of in-service courses, the teachers’ attitude towards school supervision and to determine the relationship between instructional supervision and performance of secondary schools in National examinations. The study employed an ex-post factor design targeting school inspectors, principals and heads of departments in public secondary school in Nakuru Municipality. Findings from the study established that school inspectors and principals were ill prepared for their present jobs hence handled instructional supervision poorly.Instructional supervision did not have a significant influence on secondary school performance in National examinations.