The effect of pressure of the (arbitrarily directed) interstellar magnetic field on the shape of the heliotail and consequently on space distribution of the pick-up and anomalous cosmic ray ions convected into the heliotail region is estimated in a simple model based on a Newtonian approximation. The ion distribution in the heliotail produces (via transcharging on background gas) a flux of energetic neutral atoms which can be detected from the vicinity of the Earth. Directional dependence of this flux can be used to determine the direction and possibly strength of the interstellar field. ¿ 1998 American Geophysical Union