Some scholars in recent times have attributed the fallen standard of education to the use of English as the language of instruction in Nigerian schools. Consequently, there has been a call for the use of Mother Tongue to replace English as the language of instruction. In this study the author attempts to find out whether, truly, English is responsible for the fallen standard of education and whether in the teachers’ opinion, it should be replaced with the Mother Tongue. Using 200 teachers from both private and public secondary schools as respondents, she uses a questionnaire containing 20 items for data gathering and analyses the data by frequency counts and simple percentage scores. She finds out that in the perception of the teachers, English is not responsible for the fallen standard of education and, therefore, should continue to be used as language of instruction in Nigerian schools; but it should be complemented with the Mother Tongue to facilitate understanding. She observes, however that the MTs are not developed enough for explanation of concepts and ideas in this era of new discoveries and scientific inventions and many teachers cannot teach in them. She concludes that while English and MT are used complementarily for now, the use of MT by staff and students should be encouraged.