We present VLBA observations of 1667 MHz OH maser emission from the massive star formation region G5.89-0.39 .
The observations were phase referenced allowing the absolute positions of the masers to be obtained .
The 1667 MHz masers have radial velocities that span \sim 50 km s ^ { -1 } but show little evidence of tracing the bipolar molecular outflow , as has been claimed in previous studies .
We identify 23 Zeeman pairs through comparison of masers in left and right circular polarization .
Magnetic field strengths range from - 2 mG to +2 mG , and an ordered reversal in magnetic field direction is observed toward the southern region of the UC HII region .
We suggest that the velocity and magnetic field structure of the 1667 MHz masers can be explained in the context of a model in which the masers arise in a neutral shell just outside a rapidly exanding ionized shell .