Isentropic and isocurvature axion inflationary perturbations are studied in detail. If isocurvature perturbations are present, COBE requires the inflationary Hubble constant to be rather small, HI < ∼ 10GeV, regardless of the inflation model. Microwave background anisotropies are calculated for CDM models with a mixture of axion and supersymmetric CDM. The angular power spectrum of the microwav...