The Food and Drug Administration (FDA) is announcing the availability of a guidance for industry entitled "S10 Photosafety Evaluation of Pharmaceuticals.'' The guidance was prepared under the auspices of the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH). This guidance outlines details on when photosafety testing is warranted and on possible assessment strategies; it should be read in conjunction with the ICH M3(R2) guidance, section XIV(14) Photosafety Testing. The purpose of the guidance is to recommend international standards for photosafety assessment and to harmonize such assessments that support human clinical trials and marketing authorization for pharmaceuticals. This guidance finalizes the draft guidance issued on February 4, 2013.