In this paper, the realisation of the French Liaison is investigated in a large corpus of casual speech. Considering that casual speech gives rise to a large range of pronunciation variants and that overall temporal reduction increases, one may hypothesize that French liaison tends to be less productive in this speaking style. We made use of automatic processing such as automatic speech alignments to evaluate when liaison is realized in the NCCFr corpus. Realized liaisons were examined and measured for the most frequent liaison consonants (/z/, /n/ and /t/) as a function of a liaison sites classified as mandatory, optional or forbidden. The relation between speech rate and liaison realization is also examined.