This study, investigated teachers’ perception of deficiencies in English Language among primary five Pupils in Ibadan South-West Local Government Area of Oyo State. The mixed methods design (quantitative + qualitative) was adopted. The participants were 20 teachers from 20 public primary schools in the local government area. The instruments used were Teachers’ Perceived Deficiencies of Pupils in English Language (r = 0.90) and interview guides. Data collected were analysed using the descriptive statistics for the quantitative data, while the qualitative data were content-analysed. The findings revealed that the perceived deficiencies of pupils were in the basic English language skills, vocabulary, grammatical structures and pronunciation, while large class sizes, lack of regular capacity building for teachers and limited access to learning materials were the challenges identified in the teaching of English Language. The study concluded that primary five pupils had deficiencies in vocabulary, grammatical structures, pronunciation, reading and writing and recommended that teachers should adopt effective strategies of teaching English to help address these deficiencies of pupils.