  The low-energy two neutrino-two photon interactions in the presence of
homogeneous magnetic field are studied. The cross sections in external magnetic
field are shown to be larger than in vacuum by factor $\sim (m_W /m_e)
^4(B/B_c) ^2$. The energy-loss rate due to the process $\gamma \gamma \to \nu
\bar{\nu}$ in magnetic field is obtained.
