This monograph investigates how and to what extent the transcription of East Slavic texts with the use of Latin characters reflects the true sound of Old Russian, Old Belorussian and Old Ukrainian. The research was based on four historical texts – manuscripts and old prints, dating back to the end of the 16th and 17th centuries: The Godutishki Manuscript (the oldest known copy of the 1588 Third Statute of the Grand Duchy of Lithuania), Ecphonemata liturgiey greckiey, Pacta wiecznego przymierza and Placzewnaja recz na pogrebenie [...] Karolusa Odinatsetogho. The aforementioned texts were created at a time when individual East Slavic languages had already developed from Old East Slavic, which allowed identification of common and distinctive features of Russian, Ukrainian and Belarusian phonetics recorded in texts. However, it is worth stressing that the historical texts in question are not transcriptions of texts in the modern understanding of the term – the sound of the language was only partially reconstructed in them.