The aim of this study was to explore experiences and opinions of teachers of English in Swedish upper secondary school regarding language use in the English classroom with a connection to a specific phrase in the syllabus, which mentions language use as follows “Teaching should as far as possible be conducted in English”. Seven teachers were interviewed one-on-one in a semi-structured way which emphasized their opinions and experiences. The results showed both similarities and differences in their use of language and views of the syllabus. From the interviews, it was found that the teachers all take the syllabus into consideration, but what is viewed as “as much as possible” differs between the teachers. Two situations where Swedish was often mentioned as being used were in explanations of grammar and clarifications of instructions. When teaching vocabulary a few different methods were given as examples with both languages being used, and in disciplinary actions two teachers reported using mostly Swedish, while two teachers reported using mainly English. Swedish was also seen as important for building relationships with the students, which became clearer as most teachers reported using Swedish in one-on-one interactions. The conclusion to be drawn is that the majority of the teachers prioritized the students’ understanding more than insisting on English in the classroom. Another conclusion is that the syllabus plays a role in teachers’ language use, but that adjusting their speech to the students is seen as more important.