This report describes the diagnostic approach and frenotomy in a newborn with breastfeeding difficulty, and the observation and analysis during the following 6 months. The patient was delivered normally and without complications, but showed breastfeeding difficulty during her first 5 days of life. The protocol proposed by Martinelli in 2013 was used to evaluate the lingual frenulum. After applying the protocol, the newborn was determined to require a frenotomy and the urgery was performed. The patient was reassessed using the protocol immediately after surgery and again 24 hours latter. There were improvements in the protocol scores at both reassessments. The newborn was observed and analyzed during the next six months by collecting monthly data from the vaccination card and by asking the mother for information. She was given no food supplements, pacifiers, nor sucked the thumbs, and was fed only breast milk and presented an age-appropriate weight gain. We conclude that the diagnosis using the Martinelli protocol is of fundamental importance to recognizing the need for early intervention and that the frenotomy helped improve the patient’s breastfeeding and swallowing capacity.