Photodynamic therapy (PDT) is a modern, non-invasive therapeutic method used for the destruction of various cells and tissues. It requires the simultaneous presence of three components: a photosensitizer (PS), a light source and oxygen. Precancerous skin lesions are conditions associated with a high likelihood of malignant transformation to squamous cell carcinoma. Data available so far indicate that PDT is a promising treatment method which can be successfully employed in several medical fields including dermatology, urology, ophthalmology, pneumology, cardiology, dentistry and immunology. Numerous authors therefore have studied this technique in order to improve its efficacy. As a result, significant advancement has been achieved with regard to PSs and drug delivery systems. Substantial progress was also obtained with respect to PDT for the treatment of precancerous skin lesions, several authors focusing their efforts on the study of daylight-PDT and on identifying methods of decreasing technique-related pain. This review reports on the most recent findings in PDT, with emphasis on cutaneous precancerous lesions.