['Psoriasis is an erythematosquamous dermatosis, which has strong expression of antimicrobial peptides (AMPs), imparting a high resistance to lesional skin infection. Granulysin is a proinflammatory AMP that has been found in some infection-resistant dermatoses.', 'To assess granulysin expression in psoriasis.', 'Immunohistochemical expression of granulysin was assessed in lesional skin biopsies taken from 30 patients with psoriasis and 10 normal skin specimens from healthy controls (HCs) matched for age, gender and skin site. Granulysin expression was found to be high in 11 patients (36.7%), moderate in 10 (33.3%) and low in 9 (30%). A highly significant (P = 0.001) difference in granulysin expression between patients with psoriasis and HCs was found. There were also significant differences in granulysin expression between patients with low Psoriasis Area and Severity Index (PASI) (≤ 10) and those with high PASI (> 10) (P = 0.001), and between patients with early-onset (< 40 years of age) and those with late-onset (> 40 years of age) disease (P < 0.04). There was a significant (P = 0.001) positive correlation between granulysin expression and PASI (r = 0.84) and a significant (P = 0.02) negative correlation with age of onset (r = -0.38). Patients with psoriasis hadhigh granulysin expression, which increased with increased clinical severity of the disease.'] Does granulysin expression increase with increasing clinical severity of psoriasis?