Teacher talk in the EFL classroom has been an interesting research for language specialists and also an intriguing topic among teachers. It is claimed that a foreign language (FL) should be the main language in the English as a Foreign Language (EFL) classrooms. The use of the mother tongue (L1) is not forbidden but it is advised not to use it very frequently. Code-switching is a process that very often occurs in the EFL classrooms. This process has a very negative connotation among monolinguals. They claim that teachers who code-switch do not know either language well enough to communicate. There has been a lot of discussion about the mother tongue use in the EFL classrooms. Along with the advantages of using the mother tongue, there are disadvantages which seem to be the main focus among linguists and some teachers who claim that the mother tongue in the EFL classroom can have a negative effect on language learning. The main focus of this research was to provide answers to the questions: What are the advantages and disadvantages of a mother tongue use in the EFL classroom? In which situations does the teacher switch to L1? When and why do teachers code-switch? Does code-switching occur when teachers are speaking in the FL (in English) or in L1 (in Croatian)? Participants of the research were learners (N=28, 1st and 5th graders) of English as a foreign language and their English teacher. The focus was primarily on teacher talk. Data were collected by audio-recording followed by a detailed transcription of the lessons. By analysing both English lessons, it was estimated that the teacher uses the mother tongue (Croatian) very frequently which means that code-switching occurs very often. The results have shown that the use of the mother tongue does not have significant consequences for language learning.