Netherton's syndrome is a rare autosomal recessive disorder caused by mutations of the SPINK5 gene, which encodes the lymphoepithelial Kazal-type-related inhibitor (LEKTI) protein. We observed microstructural changes and detected LEKTI activity and SPINK5 gene mutation in three Chinese patients with Netherton's syndrome. Decreased LEKTI activity was found in the skin of patients. Lamellar bodies and foci of electron-dense material were detected in the intercellular spaces of the stratum corneum. A novel homozygous splicing mutation of 1430+2 T-->G was found in the SPINK5 gene in one proband. No mutation was found in the other family.