Basal transepidermal water loss, skin thickness, blood flow and skin colour were examined before and after exposure of 28 patients with atopic dermatitis and 28 healthy controls to sodium lauryl sulphate. Transepidermal water loss was measured with an evaporimeter, skin thickness by ultrasound A-scanning, blood flow by laser Doppler flowmetry and skin colour by a chroma meter using the L*, a* and b* values, respectively. Patients with atopic dermatitis were found to have higher basal transepidermal water loss than controls (p less than 0.0001), and had an inclination towards an increased basal skin thickness (p = 0.056). No statistically significant differences were found with respect to basal blood flow or skin colour. The skin response to sodium lauryl sulphate was found to be statistically significantly increased in atopic patients compared with controls when evaluated by visual scoring and by increase in skin thickness, but not by increase in transepidermal water loss, blood flow or skin colour.