Malaysia has become one of the most important countries that produce and supply the world’s palm oil. The oil palm industry has emphasised the need for the preservation of small forest patches within oil palm plantations to sustain various species of fauna; this is a new conservation strategy for developing biodiversity-friendly oil palm plantations. The effort in documenting the species of flora and fauna in such forest patches in oil palm plantations is an action needed to display species richness, diversity and distribution within the area. Assessment of fauna species was conducted through various sampling methods in a forest patch estimated to be less than 0.30% of the total oil palm planted area of 1986 hectares at MPOB Research Station, Lahad Datu, Sabah. From the 132 species recorded, a total of 22 species of mammals (16.67%), 45 species of birds (34.09%), 11 species of amphibians (8.33%), six species of reptiles (4.54%), four species of fishes (3.03%), and 44 morpho-species of arthropods (33.33%) were identified. The fauna species identified in this forest patch provides a baseline for biodiversity assessment in other oil palm plantations. Therefore, effective sustainable oil palm management can be proven to be implemented.