  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.
