Lejeuneaceae (Marchantiophyta) is still poorly known in Sumatra. This research was conducted to explore the diversity of Lejeuneaceae in Sicike-cike Natural Park, North Sumatra, Indonesia. The species of Lejeuneaceae was observed based on the specimens collected along trails in the study site. The study reveals the occurence of 29 species, which are: Acrolejeunea (1 species), Cheilolejeunea (5 species), Cololejeunea (2 species), Colura (1 species), Drepanolejeunea (6 species), Lejeunea (6 species), Leptolejeunea (1 species), Lopholejeunea (4 species), Metalejeunea (1 species), Thysananthus (2 species). Eight species of these are newly reported for Sumatra. Those are Cololejeunea stephanii, Drepanolejeunea levicornua, D. ternatensis, D. thwaitesiana, D. tricornua, Lejeunea obscura, Leptolejeunea foliicola, and Lopholejeunea herzogiana. An identification key to the species of Lejeuneaceae from Sicike-cike Natural Park North Sumatra is provided.