The primary cause of collagen degeneration in necrobiosis lipoidica (NL) is proposed to be immunologically mediated vascular disease. Ultraviolet (UV)A1 has been used successfully to treat scleroderma in which both vascular damage and collagen dysregulation also occur. We treated six patients with NL [(five women; mean age of 32 years (range 22-70) and mean disease duration of 2.9 years (range 6 months to 5 years)] with a high-output ultraviolet (UV)A1 2-kW filtered metal halide source (Dr Hönle; Dermalight ultrA 1) having an emission spectrum of 340-440 nm. All patients had NL on the shins, which had been unresponsive to potent topical corticosteroid therapy (n = 6) and had responded minimally or not at all to TL-01 UVB (n = 2), topical psoralen plus UVA (PUVA) soaking (n = 2) or oral PUVA (n = 1) therapy. Patients received a variable number of total exposures (15-51), given 3-5 times weekly. NL resolved completely in one patient; this patient had minimal improvement after the first course of 16 exposures, but after a further 13 exposures, resolution occurred 6 months later. Two subjects obtained moderate improvement in their overall disease severity after 15 and 24 exposures, while two had only minimal improvement after 15 and 51 exposures. The remaining patient had no improvement after 16 treatments. Patients with the shortest disease duration had the greatest response. UVA1 therapy may be of benefit for the treatment of NL as an adjuvant therapy to topical corticosteroids or as a second-line alternative to other phototherapies, and may have a superior outcome in a proportion of patients.