The aim of the study was to test hypotheses derived from the application of a Dynamic Systems approach to the human development of facial expression of emotion. To ascertain whether Duchenne smiles exist before 40 gestational weeks (term age), the facial behaviour of 7 premature neonates was analyzed when their post-conceptional ages were 33/34 weeks. The faces of the neonates were videorecorded for 14 to 30 minutes and then analyzed with the FACS by Ekman and Friesen (1978), following the guidelines in the Baby-FACS (Oster & Rosenstein, in press). The literature generally suggests that the Duchenne smile emerges in the first or the second month of life and is not produced by term or preterm newborn infants. Instead, all the neonates observed showed the Duchenne smile with an intensity and a duration similar to that observed in older infants and in adults. The data are relevant because they open new questions about some aspects of the developmental trajectory of the smile.