Pterygium unguis occurs as a result of the scarring process between the proximal nail-fold and matrix and lichen planus is a typical example, although it has also been reported to occur in patients with sarcoidosis or leprosy. Lichen striatus is a childhood linear inflammatory dermatitis of unknown etiology. Many nail changes such as nail-bed hyperkeratosis, nail pitting, longitudinal ridging, onycholysis, and longitudinal fissures have been described in patients with lichen striatus, but pterygium unguis is very rare. It has been suggested that the onset and resolution of onychodystrophy correlates well with the course of skin eruption, but pterygium unguis results in permanent nail changes regardless of skin eruption. A 3-year-old boy presented with a linear papular eruption on the right hand and pterygium on the index finger. He was diagnosed with lichen striatus by histopathological findings, and the papular eruption was resolved with topical tacrolimus ointment, but the pterygium did not improve.