The Siple Station conjugate locations in the northern hemisphere are examined for the epoch 1975-1990 according to the predictions of three internal source geomagnetic fieldd models (IGRF 1980, MAGSAT 1980, Barraclough 1975) and one external field model (Mead/Fairfield) under quiet and disturbed conditions. The conjugate location systematically changes in the interval studied, making it imperative that changes be made in the locations of the northern hemisphere geophysical stations during the reactivation of Siple Station in 1985-1987.