Oral melanocytic nevi (OMNs) are uncommon benign melanocytic proliferations. Clinically, OMNs are small, well-circumscribed, flat lesions, but not uncommonly appear as slightly raised papules. They can be brown, bluish-gray, or almost black, and occasionally non- pigmented. Regarding the OMN etiology and pathogenesis, most studies have focused on its cutaneous counterpart. We present a case of OMN in a pediatric patient. A 4-year-old male was referred presenting a dark macule with regular borders, measuring 6 mm in greater diameter, located on the right retromolar pad, with a time of evolution of 15 days. The clinical diagnoses were melanotic macule and OMN. After excisional biopsy, the microscopic examination revealed junctional melanocytic nevus with lentiginous hyperplasia containing focal melanocytic atypia. After 4 months of follow-up, there is no recurrence or alteration. Thus, lentiginous junctional melanocytic proliferation with focal atypia may be observed in OMN, which should be interpreted with caution, especially in pediatric patients. Oral melanocytic nevi (OMNs) are uncommon benign melanocytic proliferations. Clinically, OMNs are small, well-circumscribed, flat lesions, but not uncommonly appear as slightly raised papules. They can be brown, bluish-gray, or almost black, and occasionally non- pigmented. Regarding the OMN etiology and pathogenesis, most studies have focused on its cutaneous counterpart. We present a case of OMN in a pediatric patient. A 4-year-old male was referred presenting a dark macule with regular borders, measuring 6 mm in greater diameter, located on the right retromolar pad, with a time of evolution of 15 days. The clinical diagnoses were melanotic macule and OMN. After excisional biopsy, the microscopic examination revealed junctional melanocytic nevus with lentiginous hyperplasia containing focal melanocytic atypia. After 4 months of follow-up, there is no recurrence or alteration. Thus, lentiginous junctional melanocytic proliferation with focal atypia may be observed in OMN, which should be interpreted with caution, especially in pediatric patients.