  We suggest an explanation for the twin kilohertz quasi-periodic oscillations
(kHz QPOs) in low-mass X-ray binaries (LMXBs) based on magnetohydrodynamics
(MHD) oscillation modes in neutron star magnetospheres. Including the effect of
the neutron star spin, we derive several MHD wave modes by solving the
dispersion equations, and propose that the coupling of the two resonant MHD
modes may lead to the twin kHz QPOs. This model naturally relates the upper,
lower kHz QPO frequencies with the spin frequencies of the neutron stars, and
can well account for the measured data of six LMXBs.
