Laugier-Hunziker syndrome is a rare benign idiopathic condition characterized by acquired macular pigmentation of the lips and buccal mucosa, often accompanied by melanonychia. Although the etiopathogenesis is not fully known, tyrosine is thought to be responsible for the pathogenesis of enzyme hyperactivity in melanin biosynthesis. We present the case of a 66-year-old woman diagnosed with Laugier-Hunziker syndrome and rheumatoid arthritis.