  Three of the averaged light curves from the X-ray spectrum of 4U 1728-34
contain triads of quasi-periodic oscillations: two kHz, an upper and a lower
one, and one low-frequency. In the present work, with the assumption that the
triads occur simultaneously and with the application of the relativistic
precession model the mass and the spin of the neutron star in the atoll source
4U 1728-34 is obtained. The consistency of the three independent estimates of
the mass and the spin is also tested. According to the obtained results, the
studied neutron star has relatively high mass and moderate spin.
