This paper examines Cicero’s use and introduction of direct speech in nine selected letters to Atticus. It shows that despite the informal traits found in the letters, Cicero is not innovative in his choice of means to introduce direct speech. The paper also notes transitional zones on the margin of the domain of direct speech and the interplay of intervening voices. In this way, it contributes to improving the knowledge of direct speech in classical Latin, which is a necessary starting point for research into its development. The analysis is divided into two parts. This part is aimed at the theoretical background, use and introduction of direct speech in the letters to Atticus.