Abstract. Adiabatic subtraction is a popular method of renormalization of observables in quantum field theories on a curved spacetime. When applied to the computation of the power spectra of light fields during inflation, the standard prescriptions of adiabatic subtraction lead to results that are significantly different from the standard predictions of inflation not only in the ultraviolet but also at moderately superhorizon wavelengths. I will review those results and contrast them with the power spectra obtained using an alternative prescription for adiabatic subtraction applied to quantum field theoretical system by Dabrowski and Dunne. This latter prescription eliminates the intermediate-wavelength effects of renormalization that are found when using the standard one. Both prescriptions lead to a vanishing power spectrum for a massless, minimally coupled scalar on exact de Sitter space.