A lithographic apparatus is disclosed. The apparatus includes an illumination system for providing a beam of radiation, a support structure for supporting a patterning device, a substrate support for supporting a substrate, a projection system for projecting the patterned beam of radiation onto a target portion of the substrate, and a thermal compensation deformation unit for compensating for a deformation of an element caused by a thermal load. The thermal compensation deformation unit includes at least one temperature sensor for sensing a temperature in at least one location on the element, and a processing unit for calculating the deformation of the element caused by the thermal load as a function of the temperature sensed at the location. The deformation is calculated using data from a computer-generated model of the element so that an appropriate correction for the deformation can be made or taken into account.