Monilethrix, a congenital disease of hair, is usually associated with mutations in keratin genes, like KRT81, KRT83 and KRT86. We conducted this study to investigate the mutation of type II human basic hair keratin hHb/KRT gene in a Han family with monilethrix and obtain information for potential pathogenic mechanism study of monilethrix. This evidence concerns the gene KRT86 and monilethrix.