The effects of scalp dermatitis (seborrheicdermatitis (SD),psoriasis, and atopic dermatitis (AD))on chemical properties of hair keratin were investigated by Fourier transform infrared (FT-IR)spectroscopy. Hairs were collected from lesional regions affected by SD, psoriasis, and AD and non-lesion al regions separately.The hairs with SD were taken from patients with ages of 16–80 years.