The effect of finite-ion-Larmor-radius averaging and of ion Landau damping on ballooning modes is investigated for a large-aspect-ratio circular-cross-section tokamak equilibrium. – Finite-Larmorradius (FLR) effects are found to be weakly de-stabilizing for small values of the FLR parameter kai, but become strongly stabilizing for kai ∼ 0.5. A residual instability driven by inverse ion Landau damping persists, however, at shorter wavelengths (kai > 0.5).