Lateral periodontal cysts (LPCs) are rare odontogenic cysts of developmental origin. A 52-year-old man presented with an asymptomatic gingival swelling located between the mandibular left canine and first premolar, both of which were vital. Radiography showed a well-circumscribed radiolucent area and loss of the lamina dura around the tooth socket in contact with the lesion and of the interproximal buccal bone. The lesion was enucleated. The defect was immediately grafted with a 1:1 mixed autologous and heterologous bone graft covered with a collagen membrane. Histology confirmed the diagnosis of LPC. At 12- and 24-month clinical and radiologic follow-up, complete bone and periodontal healing was found, with no sign of recurrence.