Data relative to trees growth rates seems fragmentary for many tropical species in the Congo Basin, and several studies question the growth diameter values used by the government. In this study, an approach for tree-ring measurement using Geographic Information System tools (softwares ArcMap and Photoscan) was tested on two commercial species from tropical African rainforest (Iroko- Milicia excelsa and Afrormosia- Pericopsis elata). The aim of this study was to evaluate the precision gain of the GIS tools used in the estimates of diameter increments and to compare the results with the values recommended by the Congolese Forest Administration (DRC). Diameter increments were calculated through semi-automatic procedure to the nearest 10-5 mm. For all classes of diameter, the mean annual increment is 6.65mm/year for iroko and 4.66mm/year for afrormosia. We observe that the values used by the forest authority (5mm/year and 4 mm/year for iroko and afrormosia respectively) seem to under-estimate growth rhythms. The method used can be applied to other commercial tree species with distinct and annual tree-rings for providing new data in order to fill knowledge gaps on the growth rates of tropical trees.