In 6 patients with Sjögren-Larsson syndrome (SLS), the urinary excretion of leukotriene B(4) (LTB(4)) and omega-hydroxy-LTB(4) was found to be highly elevated, whereas omega-carboxy-LTB(4) was absent. This abnormal pattern of urinary excretion of LTB(4) and its metabolites appears to be unique to patients with SLS and offers a new approach to the diagnosis of this disorder. Moreover, defective inactivation of LTB(4) might be of pathophysiologic significance in the disease.