Principal aims of the present study was to assess the activity of the orbicularis oris muscle (OM) and of the masseter, temporalis and buccinator muscles (MM, TM and BM) (i.e. the muscles in charge of sucking during breastfeeding) during breastfeeding and bottle-feeding by means of SLI. The new Chicco feeding bottles Natural Feeling (Natural Fit) 0m+, 4m+ and 6m+ were used according to the age of the infants.