Purpose: to evaluate the lingual frenulum and breastfeeding in infants from a maternal-perinatal referral center, as well as to monitor infants with ankyloglossia up to six months of age. Methods: a cohort study conducted at the Instituto Nacional Materno Perinatal - Maternidad de Lima in Lima, Peru. The consecutive intentional sample consisted of 304 newborns and their respective mothers, evaluated during December 2017 and January 2018, which were the baseline of the study. A clinical evaluation of the lingual frenulum adapted and the Clinical Evaluation of Breastfeeding Efficacy (CEBE) scale, was performed. Results: of the 304 newborns, 15 (4.9%) were considered with altered frenulum, and only 4 (26.7%) presented a low score in CEBE. The mean of the CEBE score was 9.3. (DP=1.35, Min=3, Max=10). Of the follow-up infants, only 2 (13.3%) persisted with breastfeeding difficulties for which frenotomy was indicated. Conclusion: This study demonstrates the low prevalence of ankyloglossia in infants, as it does not indicate a trend of difficulty or negative interference in breastfeeding.