In rheumatoid arthritis various pro-inflammatory metabolites of arachidonic acid (AA), such as leukotriene B4 (LTB4) and prostaglandin E2 (PGE2), contribute to tissue destruction and pain. In contrast to AA, which is an omega-6 fatty acid, the omega-3 fatty acids, after having been liberated from the cell membrane phospholipids, are further converted into the non- or anti-inflammatory eicosanoids LTB5 and PGI3. AA concentration is an important regulatory step in the synthesis of both prostanoids and leukotriens. Dietary supplementation with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has therefore been used to decrease the ratio of AA to EPA or DHA to obtain beneficial clinical effects. EPA and DHA are found in animal fat and are quite expensive compared to their precursor alpha-linolenic acid (alpha-LNA) found in flaxseed oil. We, therefore, performed a placebo-controlled trial with alpha-LNA in 22 patients with rheumatoid arthritis, using a linoleic acid preparation as a placebo. After a 3-month follow-up, the treatment group showed an increased bleeding time, but the clinical, subjective (global assessment, classification of functional status, joint score index, visual analogue scale, pain tenderness score) and laboratory parameters (haemoglobin, erythrocyte sedimentation rate, C-reactive protein) did not show any statistical alterations. AA, EPA and DHA did not change either in spite of a significant increase in alpha-LNA in the treatment group. Thus, 3-month's supplementation with alpha-LNA did not prove to be beneficial in rheumatoid arthritis.