We have obtained adaptive optics images and accurate radial velocities for 7 very low mass systems, in the course of a long term effort to determine accurate masses for very low mass stars (M<0.6 Solar Mass). We use the new data, together with measurements from the litterature for some stars, to determine new or improved orbits for these 7 systems. They provide masses for 16 very low mass stars with accuracies that range between 0.2% and 5%, and in some cases a very accurate distance as well. This information is used in a companion paper to discuss the Mass-Luminosity relation for the V, J, H and K photometric bands.
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