Bornean rain forests are characterised by a supra-annual cycle of massive reproduction. This long reproductive cycle is considered the reflection of an adaptive trait to accumulate enough phosphorus (P) for reproduction on P-poor tropical soils. However, the relationships between the reproductive cycle of trees and soil P availability have rarely been studied. Here, we analysed the periodicities of flower and fruit litterfall for 53 tree species in six forests on contrasting soil substrates (P-poor ultrabasic and relatively P-rich non-ultrabasic soils) at different altitudes (1700, 2700 and 3100 m) on Mount Kinabalu, Borneo. A Fourier time-series analysis was performed to identify the dominant cycles of flower and fruit litterfall from 1996 until 2003, using the long-term monitoring data set obtained by earlier studies. The length of cycles varied among species, from 8 to >200 weeks and from 4 to >200 weeks for flower and fruit litterfall, respectively. Many species showed supra-annual cycles of flower and fruit litterfall. Species on P-poor ultrabasic soils often showed a longer cycle of flower litterfall than that on P-rich non-ultrabasic soils at the same altitudes, when analysed for each genus separately. These results will be discussed in relation to altitude and other factors such as fruit type and phylogeny.