Clonal Eucalyptus plantations in the Pointe-Noire region have been established on sandy and nutrient poor soils, and carry potential risk of depleting water and nutrient. To assess these risks, water and nutrient budgets should be calculated. However, the accuracy of hydrological models is strongly dependent on a realistic description of root distribution in soil. The spatial distribution of root systems in a chronosequence of clonal stands was then studied, using root intersect counting. The stands were 3 months, 6 months, 1 year, 2 years and 9 years old. For each stand we studied three vertical profiles perpendicular to the planting row at different spacing from a representative tree. The profiles were divided into square grid cells of 25cm², and the number of roots belonging to three diameter classes (between 0.1 and 1, 1 and 10mm, and over 10mm) were counted in each grid cell. The profiles were 2.50m wide (half the distance between the planting rows) and 3m deep, except for the two youngest stands (1.5m deep). Spatial statistical analyses and analysis of variance were carried out to describe root distributions and their spatial and temporal changes. We observed that: These patterns of distribution allow rapid access to soil water and nutrients, reduce loss by deep drainage, and may partially explain the fairly high productivity of these plantations.