Leaf trait associations promote functional understanding of plant carbon economy. During the ontogenetic development of trees from understory seedlings to canopy dominants, leaf trait associations may change in response to the micro environmental conditions. Individual leaf area (LA) varies widely within and across species. Despite the importance of LA in plant strategies, it has received less attention compared to other leaf traits in community-wide studies. Here, we examined how LA and its association within other leaf traits change during ontogeny across co-occurring species in a Malaysian lowland tropical rainforest. Leaves of seedlings, juveniles and adult trees were collected for measurements of LA, leaf mass per area, leaf dry mass contents, thickness, toughness and mass-based nitrogen contents, and their associations were examined. Significant positive correlations between different stages were found for every trait except for LA between seedlings and juveniles. All traits but LA tend to be similar coordination across ontogeny. These results suggest that large change in optimal LA during ontogeny, possibly in relation to vertical gradient of environmental conditions within the forest.