Corpus based text-to-speech systems currently produce very natural synthetic sentences, though limited to a neutral inexpressive speaking style. Paralinguistic elements are some of the expressive features one would most like to introduce. In this paper, we describe a new method for introducing laughter and hesitation in synthetic speech. Thanks to a small dedicated acoustic database, this method can successfully render transitions between speech and paralinguistic elements. We validate it here for French but extension to other languages should be straightforward.