The Main Sequence (MS) stars are by far the most numerous class in the Universe. They are often somewhat neglected as they are relatively quiet objects (but exceptions exist) though they bear testimony of the past and future of our Sun. An important characteristic of the MS stars particularly the solar-type ones is that they host the large majority of the known extrasolar planets. Moreover at the bottom of the MS the red M dwarfs pave the way to understanding the physics of brown dwarfs and giant planets themselves. We have measured very precise angular diameters from recent VINCI/VLTI observations of a number of MS stars with spectral types between A1 and M5.5 which already cover a wide range of effective temperatures and radii. Combined with precise Hipparcos parallaxes photometry spectroscopy as well as the asteroseismic information available for some of these stars the angular diameters put strong constraints on the detailed models of these stars and therefore on the physical processes at play.