Topical photodynamic therapy with 5-aminolevulinic acid (ALA-PDT) is a well-established treatment regimen for superficial epithelial skin tumours, but it is evident that inflammatory diseases of the skin and virus-induced lesions can also profit from PDT. Depending on the light dose applied, either cytotoxic effects resulting in tumour destruction or immunomodulatory effects resulting in improvement of inflammatory conditions occur. Patients with localized scleroderma that had been unresponsive to various treatments, including PUVA or bath-PUVA therapy, respond very well to topical ALA-PDT performed repeatedly. In contrast to PUVA therapy, no carcinogenic potential is being discussed for PDT. Also, HPV-induced skin lesions might provide a possible indication for topical ALA-PDT. The rapidly proliferating cells in viral acanthomas accumulate ALA-induced protoporphyrin IX (PPIX) selectively when compared to the surrounding non-infected cells. The efficacy of topical ALA-PDT in the treatment of recalcitrant foot and hand warts has been shown in a placebo-controlled, randomized, double-blind trial. Furthermore, case reports describe a good response of other virus-induced diseases, for example condylomata acuminata and epidermodysplasia verruciformis, to topical PDT with ALA. However, controlled clinical trials are still needed to demonstrate more fully the effectiveness of PDT for inflammatory skin diseases.