A WKB theory is formulated for large‐nballooning modes in axisymmetric, toroidal plasmas with sheared equilibrium flows. The validity of the standard ballooning representation is severely restricted in the presence of sheared toroidal flow, despite the fact that to leading order in (1/n), wherenis the azimuthal number, the eigenmode equation contains only derivatives along a field line. Necessary and sufficient conditions for stability are obtained in a high‐beta ordering for rigid toroidal rotation as well as field‐aligned flows.