The purpose of this study is to verify if the traditionally acknowledged lenition of intervocalic plosives in the varieties of Southern Italy also applies to voiceless fricatives. Data from a recent corpus of semi-spontaneous speech collected in Naples and Palermo are analysed according to the parameters of duration, intensity, and voicing. It is demonstrated that, in the intervocalic position, the realisations of /s/ and /f/ are significantly shorter, whereas intensity does not prove to be affected by the phonotactic position; sonorization does occur, to some extent, in the Neapolitan data, being marginal among the Sicilian speakers.