The eigenvalue problem of whistler propagation in a magnetic trap is analyzed in the slab model. The plasma is comprised of three regions: (I)a≤x<∞, (II) 0≤x≤a, and (III) −∞<x≤0. Region II contains a hot‐electron component and possesses a smaller magnetic field. The hot electrons have a temperature anisotropy and tend to destabilize the whistler mode. The dip in the magnetic field tends to confine the mode to region II.