The linear stability criterion of the tearing mode in the magnetotail current sheet with nonzero normal component of the equilibrium magnetic field first obtained by Lembege and Pellat [1982> considered the electrons to be trapped in the current sheet. This condition is significantly modified when electron-to-ion temperature ratio is small, due to the contribution of transient orbits to the perturbed electron density integrated over the flux tube. In contrast to the previous result marginal stability may be reached under realistic conditions in the near-Earth tail current sheet during late substorm growth phase. ¿ 1998 American Geophysical Union