The study assessed the factors influencing the use of instructional materials on learning of English Language in secondary schools in Afijio Local Government Area, Oyo State. The study employed descriptive survey design. The population used for this study comprises of all English Language teachers in 22 public junior secondary school of Afijio Local Government Area, Oyo State.  Fifty (50) teachers were selected as sample. The instrumentation used for the collection of data is a structured questionnaire titled “Factors Influencing the uses of Instructional Material in the teaching of English Language Questionnaire”. The instrument was validated by experts. Four research questions guided the study. The findings showed the available instructional materials used in the teaching of English Language in junior secondary schools in Afijio Local Government Area, Oyo State; it revealed how adequate are the instructional materials; also revealed the attitude of teachers towards the use of instructional materials in the teaching of English Language and revealed the environmental factors influencing the use of instructional materials in teaching of English Language. Based on the findings, it was recommended among others that English Language teachers should endeavour to use and try to improvise instructional materials for effective teaching of English Language in the secondary schools.