Midline diastema is a space between the central incisors. Although physiologic transitory maxillary midline diastema is observed in children during eruption of maxillary anterior teeth in most cases, it is self-corrected after eruption of maxillary canines. However, midline diastema unrelated to the eruption of teeth has been observed owing to various etiologic factors. Treatment to align the central incisors depends on the predisposing factors.