  The reentrant nature of Peak Effect is established in a single crystal of
2H-NbSe_2 via electrical transport and dc magnetisation studies. The role of
disorder on the reentrant branch of PE has been examined in three single
crystals with varying levels of quenched random disorder. Increasing disorder
presumably shrinks the (H,T) parameter space over which vortex array retains
spatial order. Although, the upper branch of the PE curve is somewhat robust,
the lower reentrant branch of the same curve is strongly affected by disorder.
