As a means of adaptation to extreme habitats, mangrove plants produce a variety of secondary metabolic substances that have the potential as herbal medicines. Empirically, coastal communities have utilized and proven the medicinal properties of mangrove plants. The study’s objective was to determine the species diversity of mangrove plants and their use as herbal medicine in the Coastal of Pesawaran, Lampung Province. Mangrove plant diversity was obtained through vegetation analysis and the diversity index calculation. The use of mangroves as medicine was obtained through in-depth interviews followed by descriptive analysis and calculation of species use value, plant part value, and fidelity level. The results showed that the mangrove forest on the Pesawaran Coast consisted of 21 mangrove species from 12 families, with a moderate diversity index (H’= 1.9312). Most of the users of mangrove plants as medicine ethnically were Bugis (55%), aged over 40 years (62.5%), have an income ranging from 100--167 USD / month (54%), and have secondary education (37.5%). The community uses Avicenia alba as an antiseptic, Acanthus ilicifolius as an antiseptic, Rhizophora apiculata as an antiseptic and analgesic, and R. stylosa as an antiseptic and anti-rheumatism. The Species use value of R. apiculate was the highest (0.25), while the other three species only reached 0.125. Leaves and bark were parts of the plant used as medicine, where leaves have the highest plant part value of 91.67%, and the remaining 8.33% was bark. The highest fidelity level was obtained by R. apiculate as an antiseptic (88%), followed successively by R. stylosa as an antiseptic (50%), R. stylosa as an analgesic, and A. alba as an antiseptic (13%).