Acronyms are used more and more nowadays: this article describes their pronunciation in French and in Italian. Rules are proposed, so that a text-to-speech converter may know whether it must spell or read acronyms, and which way. Our analysis, which gave rise to a computational realisation, leans on the number of letters which constitute acronyms, on the vowel/consonant opposition, as well as on the distribution between continuous and momentary consonants.