A 46-year-old female with hyperthyroidism presented with asymptomatic dark pigmentary changes to her lips, oral cavity, and nails over 10 years; none of her family members had similar symptoms. On physical examination, we found diffuse dark-colored hyperpigmented macules on her buccal mucosa, lips, and tongue (Panel A), and longitudinal melanonychia was noted on the right index fingernail with multiple periungual hyperpigmentation (Panel B), as well as on the toenails. Biopsy of the lower lip revealed focal increase in pigmentation at the basal layer. Laboratory tests to evaluate adrenal function showed that serum cortisol and ACTH levels were normal. In addition, there was no specific finding in gastrointestinal endoscopy performed to differentiate Peutz-Jeghers syndrome (PJS). Finally, we diagnosed the patient as having Laugier-Hunziker syndrome (LHS) after we excluded Addison’s disease and PJS, so we decided to observe progress only without any treatment. LHS is known to be a benign and acquired disease characterized by melanotic pigmentation of the oral mucosa, lips, fingers, and nails; unlike Addison’s disease or PJS, it does not require treatment because there are no systemic manifestations. Therefore, clinicians need to reassure patients diagnosed with LHS that it is sufficient to follow up periodically without treatment.