The beneficial effects of ultraviolet (UV) radiation on atopic dermatitis has been appreciated for many years. While broadband UVB and psoralen UVA have been the mainstay of phototherapy for some time, the past 5 years have seen the introduction of phototherapeutic modalities, including UVA-1 and 311nm UVB. The best modality and mode of usage is dependent on the type of atopic dermatitis, severity and body site. T lymphocytes play an important role in disease pathogenesis and UV radiation has profound effects on skin and systemic immune responses.