An illumination system for a microlithography projection exposure apparatus for illuminating an illumination field (65) with the light from an assigned light source (11) comprises a pupil shaping unit (15, 30) for receiving light from the assigned light source (11) and for generating a predeterminable basic light distribution in a pupil plane (31) of the illumination system and a transmission filter (36) assigned to the pupil shaping unit (15, 30) and having at least one array of individually drivable individual elements for the spatially resolving transmission filtering of the light impinging on the transmission filter in or in proximity to a pupil plane (31, 35) of the illumination system, the transmission filter (36) being designed for generating a predeterminable correction of the basic light distribution. An illumination system of this type can generate a multiplicity of location-dependent intensity distributions in a pupil plane of the illumination system, a high transmittance being ensured. The location-dependent intensity distribution in the pupil plane generates an angle-dependent intensity distribution on the illumination field of the illumination system which can be optimized for a mask structure to be imaged.