Propositions about an abnormal fatty acid metabolism in atopic dermatitis patients prompted us to compare the phospholipid fatty acid composition and LTB4 release of neutrophils from 15 atopic dermatitis patients, as well as the adipose tissue triglyceride fatty acid composition, to that of 15 healthy controls matched by age, gender, and smoking habits. We found no differences in the tissue fatty acid composition between the two groups. The release of leukotriene B4 from Ca-ionophore-stimulated neutrophils in patients was on the average only 42% (p less than 0.001) of that measured in the control group, despite the very similar arachidonic acid contents of these cells. Our study does not support the assumption of an abnormal fatty acid desaturation in atopic dermatitis patients. Rather, the capacity to release and/or convert arachidonic acid into leukotrienes in neutrophils appears to be affected by this disease.