Objective. Celiac disease (CD) is characterized by villous atrophy with crypt hyperplasia and inflammation of the small intestinal mucosa leading to disturbed epithelial transport. In untreated CD, fat malabsorption can occur. The aim of this study was to investigate the profile of serum fatty acids in newly detected CD before and after treatment with a gluten-free diet. Material and methods. Serum samples were obtained from 50 adults with active CD showing small-bowel mucosal villous atrophy, from the same patients in remission after treatment with a gluten-free diet, and from 59 controls. Serum fatty acids were analyzed by capillary gas-liquid chromatography. Results. Especially the proportions of arachidonic acid (20:4 n-6) and the long-chain polyunsaturated fatty acids of the n-3 family docosapentaenoic acid (22:5 n-3) and docosahexaenoic acid (22:6 n-3) were decreased in subjects with active CD. Serum levels of these fatty acids increased during remission, but still remained significantly lower than control values. Levels of unsaturated and monounsaturated fatty acids were generally increased in subjects with CD compared with those in controls. Conclusions. In patients with CD, determination of serum fatty acid composition can be considered if the dietary history or symptoms suggest an inadequate supply of long-chain fatty acids.