Many trees in tropical rain forest exhibit interlocked grain. This phenomenon was observed, using a splitting method, on 10 trees from different genera in French Guiana. There were rather strong variations between and within trees. Different indexes were used and compared to describe this interlocked grain. Previous results have shown that the rupture energy necessary to create a radiallongitudinal surface by wood splitting grows more than 2 or 3 times with interlocked grain occurrence. Moreover, radial splitting of large tropical trees with high density wood is more prone to appear due to the decrease of the ratio between rupture energy and Young's modulus when wood density increases. Finally the long lasting high level of maturation stress in tropical trees growing in primary forest means a very high level of stored elastic energy in the trunk that could be dangerous for the living tree. Interlocked grain can be a good solution to prevent the risk of radial splitting for these adult trees.