Ultraviolet B (UVB 290-320 nm) radiation has been used in the treatment of different skin diseases. Light sources with narrowband UVB output spectrum have been developed with the aim of increasing the rates of beneficial to side effect profile of the treatment. Narrowband UVB phototherapy using fluorescent lamps (TL01, 311∓2nm) has been widely adopted over the past 10 years. Monochromatic Excimer Light (MEL) represents a new source of narrow-band UVB emitting at 308 nm and guarantees a safe and effective approach to different chronic and recurrent skin diseases thanks to its potent and selective immunosuppressant action.