The article deals with pronunciation teaching and the most frequent errors. In the first part there are described different approaches of pronunciation teaching as well as teaching frequently used methods of teaching pronunciation. The necessity of pronunciation practice is explained on examples of factors that affect intelligibility and the role of mother tongue in communication. The second part is devoted to the description of students`strategies of sound replacement and substitution and to the most difficult sound /0/ for Czech students. A short research about pronunciation the th - /0/ sound at a chosen sample of English students at the Institute of Technology and Business is shown in the final part othe text.