Background: Laugier-Hunziker syndrome (LHS) is a rare, benign, acquired disorder that is usually characterized by hyperpigmentation of the oral cavity and lips, along with longitudinal melanonychia. Till date, its characteristics have not been investigated in a large number of patients in a single-center study. Objective: This study aimed to investigate the clinical, dermoscopic, and histological characteristics of LHS. Methods: We retrospectively reviewed the medical records, biopsy specimens, and clinical and dermoscopic photographs of 21 patients diagnosed with LHS at Pusan National University Hospital (Busan and Yangsan) over a period of 15 years (2008∼2022). Results: Among the 21 patients, 20 patients (95.2%) were female and one patient (4.8%) was male, and the mean age was 56.0 years (range: 18∼75 years). The lower lip (95.2%) was the most frequently affected oral mucosa, followed by the upper lip (81.0%), buccal mucosa (66.7%), tongue (57.1%), gingiva (42.9%), and palate (14.3%). The nails were the most commonly affected extraoral site, and in our study, eight of 21 patients (38.1%) presented with periungual lesions. Based on the dermoscopic findings, a globular pattern was the most common. Histologically, the lesions showed epithelial acanthosis and increased basal keratinocyte melanin without an increase in the number of melanocytes. Conclusion This is the first study to investigate the clinical, dermoscopic, and histological characteristics of patients with LHS. The results of this study could be helpful in understanding LHS.