A simple two-fluid theory of the drift kink instability is developed. The validity of the theory is restricted to the regime where the ion gyroradius is small in comparison with the sheet thickness &rgr;i≪L and wavelength &rgr;iky≪1. Analytic expressions are derived for the real frequency and growth rate. For the limited region of parameter space where two-fluid theory is applicable, the analytic expressions are in excellent agreement with a full Vlasov solution [Daughton, 1999>. ¿ 1999 American Geophysical Union