Hydrographic data of about 500 deep casts obtained by several participating ships during the International Indian Ocean Expedition have been utilised in the valuation of the surface currents in the Indian Ocean during winter and summer seasons. The data have been averaged over 5° squares for the purpose of estimation of the surface currents using geostrophic approximation and 1500 m depth has been chosen as the reference level roughly coinciding with the boundary of the main •thermocline. The resulting surface current, systems are shown in Figs. 1 and 2.