Orbits of new Hipparcos binaries: III

We present apparent orbits and fundamental parameters of three pairs of early M-type dwarfs. The orbital elements are determined from speckle interferometric observations at the 6-m BTA telescope of the Special Astrophysical Observatory. The orbits of two pairs, HIP39402 and HIP 104565 are built for the first time. The orbit of HIP106972 is revised using new observational data obtained in 2007–2008. The periods of motion and semimajor axes of all the three binaries have very similar values, namely 13 years and 5.5–6 AU, respectively. The dynamical total masses of the systems, obtained from the orbital elements are determined with quite large errors of 25–40%, which is due to the parallax errors.