Mucosal leishmaniasis (ML) is a parasitic disease affecting the mucosa of the upper respiratory tract and oral cavity. It is most prevalent in Central and South America, whereas cases in the Old World are relatively rare. Herein, we present the case of an immunocompetent man from Tunisia with a long-delayed diagnosis of ML, characterized by lesions in the nasal mucosa without cutaneous involvement. This report underlines the importance of multidisciplinary care and adherence to follow-up in managing this disease. Clinicians should remain vigilant regarding this parasitosis, its potential complications, and the need for accurate diagnosis and treatment.