This study is aimed at to examines the respondence opinion on the application of Henri Fayol's principle of discipline to the administration of Secondary Schools in Niger State, Nigeria. The study consist of five research objectives, research questions and hypotheses respectively. The study also specifically concentrate on the aspect of discipline as one of the administrative principles of Fayol's and covered the following area as communication, decision making process, maintenance of facilities, staff development, and administration of examination, inspection and supervision. The study involves the use of questionnaire techniques to solicit responses from staffs in public and private secondary school of the study area in which timely lasted for five weeks. The study adopted descriptive survey design to assess the opinions of secondary school principals and teachers on the application of Henri Fayol's principle of discipline from the population of 585 principals and 6595 teachers in Niger State. A sample of 50 principals and 660 teachers from 50 public and private secondary schools of the study area were randomly drawn. The instrument used for the collection of data was tagged "application of Fayol's discipline principles Questionnaire AFDPQ)". However research question were five sections in which range at ten (10) for each. Instrument was developed using five points scale questionnaire (strongly agreed, agreed, undecided, disagree and strongly disagree). The instrument were validated by three qualified PHD's experts in admin and planning unit of Ahmadu Bello University, Zaria. However, research questions were subjected to descriptive statistics involving tabular form and percentages while hypotheses were tested using inferential statistics of t-test at 0.05 level of significance. It was found that opinion of public and private secondary school staff did not differ significantly on application of Henri Fayol's principle of discipline on communication, decision making process, maintenance of facilities and administration of examination, inspection and supervision. However, respondents' opinions in public and private secondary schools on the application of Henri Fayol's principle of discipline to staff development differed significantly. The researcher recommended among others that the Federal Government of Nigeria, through Federal and State Ministry of Education, should organise seminars, workshops and conferences for teachers on the use of Henri Fayol's principles of discipline for effective managemment and administration of schools. Principals and teachers in secondary schools should establish effective creteria in improving communication through periodic meetings, forming press commitees and delegation of authority among other actions.