Abstract. Uddin M, Chowdhury FI, Hossain MK. 2020. Assessment of tree species diversity, composition and structure of Medha Kachhapia National Park, Cox’s Bazar, Bangladesh. Asian J For 4: 15-21. Tree species diversity assessment is considered an essential task to design robust conservation action plans of Protected Areas (PAs). Numerous researches have assessed tree diversity of different PAs of Bangladesh but tree diversity of Medha Kachhapia National Park (MKNP) is still unknown due to lack of research initiatives. It hinders forest managers of this PA to plan and implement conservation actions successfully. To this end, the study carried out a systematic sampling to ascertain composition, distribution, and diversity of tree species available at MKNP of Bangladesh. Findings revealed that representation of tree diversity of MKNP was very poor. Only 10 tree species representing 6 families were identified. Besides, MKNP was dominated by different Dipterocarpus spp. especially with Dipterocarpus costatus. Dominance in height and diameter classes and high Important Value Index (133.94) of D. costatus indicated that the tree might possess a suitable habitat in MKNP to maintain optimum dispersal, development, and growth. However, recent plantation activities with exotic Acacia auriculiformis and intensified human-induced disturbances might hamper its habitat. Thus, to conserve the habitat of D. costatus and remaining forest resources of MKNP, reforestation efforts should be shifted from exotic to native tree species, and community anthropogenic disturbances should be minimized.