  In the weak field approximation, the nonsymmetric gravitational theory has,
in addition to the Newtonian gravitational potential, a Yukawa potential
produced by the exchange of a spin $1^+$ boson between fermions. If the range
$r_0$ is of order $30$ kpc, then the potential due to the interaction of known
neutrinos in the halos of galaxies can explain the flat rotation curves of
galaxies. The results are based on a physical linear approximation to the NGT
field equations and they are consistent with equivalence principle
observations, other solar system gravitational experiments and the binary
pulsar data.
