Until recently, various therapies for localized scleroderma have been used with limited success. Recently, phototherapy, with or without psoralen, was proposed as a successful treatment modality. The aim of this study was to evaluate the effect of broad-band low-dose ultraviolet A (UVA) phototherapy in patients with localized scleroderma, using a new method for evaluation. Twelve patients complaining of morphea were exposed to UVA irradiation at a dose of 20 J/cm2 3 times per week for 20 sessions. Selected covered plaques served as internal controls. The efficacy of therapy was judged clinically by sequential inspection and palpation. In biopsy specimens from exposed and covered plaques stained with hematoxylin and eosin (H & E) and Masson trichrome stains, the concentration of collagen per dermal surface area was measured with the use of a computerized image analyzer. All patients reported remarkable softening of skin lesions, confirmed by sequential palpatory assessment. A significant reduction in the mean concentration of collagen per surface area was detected in the plaques exposed to UVA (the P value being 0.007, P<0.01), whereas in the covered plaques the difference was not statistically significant (the P value being 0.10, P>0.05). The conclusion is that low-dose broad-band UVA phototherapy is a very effective and safe treatment modality for localized scleroderma.