In 2018 the area of plantation forests in Indonesia reached 8,668,670 ha. Pests and diseases have been considered as critical factors in sustainable production of plantation forests in the humid tropic areas. With the introduction of new plant species such as fast-growing plants of acacias and eucalypts, new pests and diseases have become emerging threats. Several pathogenic fungi and bacteria have been recorded in plantation forests in Indonesia since their early establishment. The fungal species associated with the most common diseases include Ceratocystis manginecans (Ceratocystis wilt and dieback), Ganoderma philippii (red root rot), Phellinus noxius (brown root rot and heart rot) and Fusarium spp. (Fusarium wilt), whereas the major bacterial pathogens are Ralstonia spp. (bacterial wilt) and Xanthomonas spp. (leaf streak). As one key component of integrated pest management, biocontrol measure plays significant roles in managing major diseases of tropical plantation forests in Indonesia. A number of forestry companies have put development of biocontrol agents as one of their priority research programs. For this scenario, antagonists have been collected and isolated from different ecosystems. This paper reviews development of biocontrol agents to manage major diseases of tropical plantation forests in Indonesia.