A projection objective for microlithography for imaging an object field onto an image field includes: a first partial objective for imaging the object field onto a first real intermediate image; a second partial objective for imaging the first intermediate image onto a second real intermediate image; a third partial objective for imaging the second intermediate image onto the image field, the third partial objective including an aperture; and a first folding mirror for deflecting radiation toward a concave mirror and a second folding mirror for deflecting the radiation from the concave mirror toward the image plane; in which the projection objective is an immersion projection objective in which during operation an immersion liquid is situated between a last lens surface and an image plane, and at least one surface of at least one lens in the second partial objective has an antireflection coating including at least six layers.