© SAGE Publications.To date, no study has evaluated changes in oral labial angle as preterm infants mature. The main purpose of this study was to document goniometer measurements of the labial angle of the mouth in preterm infants, to assess changes with development, to compare to findings in healthy term infants, and also evaluate oral motor reflexes in these groups. Seventy-eight preterm infants and 45 healthy term infants were recruited for the prospective study. Labial angle was assessed via goniometer, and oral motor reflexes and the volume of milk ingested were evaluated. There was significant difference between term and preterm infants' labial angles (P <.01). The distribution of preterm infants' angles were similar to term infants' by 36 to 40 weeks' postmenstrual age. Goniometer measurements of the oral labial angle may reveal oral motor performance in preterm infants and may be relevant for feeding skills assessment in this group of infants.