Phototherapy with ultraviolet (UV) irradiation of wavelengths between 280 and 320 nm (UV-B) is a safe and effective treatment for a variety of inflammatory skin diseases. In addition to standard broad band UVB, narrow band phototherapy with fluorescent bulbs emitting near monochromatic UV between 310-315 nm has become an important treatment for diseases such as psoriasis, atopic dermatitis or vitiligo. Other diseases respond favorably to narrow band UV-B phototherapy, the number of potential indications for such phototherapy is continuously growing. The differential effects of narrow band UV-B phototherapy in comparison to other UV phototherapies, as well as new and established indications for this treatment modality are reviewed.