The intermediate disturbance hypothesis (IDH) predicts that the highest species diversity occurs at an intermediate level of disturbance. The validity of the IDH remains contentious in tropical forests because the IDH has been supported in tropical dry forests but often not in humid tropical forests. We addressed the following questions: (1) is the IDH valid in humid tropical forests of Borneo; (2) how does the disturbance index (DI) influence conformity to the IDH; and (3) does the rainfall regime influence conformity to the IDH within the tropical biome?