© 2017, Marmara University. All rights reserved.Abnormal skin reactions may be observed in the skin subject to sunlight and photoreactive xenobiotics. Phototoxicity can be defined as the response to the combined exposure of the skin to photoreactive xenobiotics and light. Phototoxicity occurs with symptoms like erythema, edema, skin irritation and itching. The UV-absorbing properties of various organic chemicals, can lead to induction of phototoxicity by this substances. Number of drugs and cosmetics, which have such properties, are increasing from day to day. Several test methods were developed to determine the phototoxic potential of chemical substances. Particularly after the acceptance of 3R principle, many alternative methods were developed, validated and accepted by the regulatory authorities, for the evaluation of the potential toxic effects of the chemicals. On March 11, 2013, the commercial sale of all cosmetics and personal care products, which were tested on animals, was banned in the European Union and since then the safety evaluation of the cosmetics is being conducted by alternative In vitro toxicity tests. These tests, including tests for phototoxicity, are suitable for many toxicity studies. This review will focus the mechanisms of phototoxicity and the alternative test methods used for the detection of this particular toxic effect.