Maxepa contains eicosapentaenoic acid (EPA) (171 mg/capsule) and docosahexaenoic acid (DHA) (114 mg/capsule). EPA acts as an alternative substrate to arachidonate, leading to the formation of the less proinflammatory prostaglandins ('3' series) and leukotrienes ('5' series). If Maxepa has anti-inflammatory properties it could be expected to reduce the requirement for NSAIDs in patients with RA. This has not been investigated nor has Maxepa therapy been studied over a full 1-yr period. Sixty-four patients with stable RA requiring NSAID therapy only were studied. Patients received either 10 Maxepa or air-filled placebo capsules per day for 12 months. All then received placebo capsules for a further 3 months. Patients were reviewed at 3-monthly intervals. NSAID requirement at entry visit for each patient was assigned as 100%. Patients were instructed to slowly reduce their NSAID dosage providing there was no worsening of their symptoms. Clinical and laboratory parameters of RA activity were also measured. There was a significant reduction in NSAID usage in patients on Maxepa when compared with placebo from month 3 [mean (95% C.I. for mean) requirement--71.1 (55.9-86.2)% and 89.7 (73.7-105.7)%, respectively]. This effect reached its maximum at month 12 [40.6 (24.5-56.6)% and 84.1 (62.7-105.5)%, respectively] and persisted to month 15 [44.7 (27.6-61.8)% and 85.8 (60.5-111.1)%, respectively] (P <0.001, ANOVA). These patients were able to reduce their NSAID requirement without experiencing any deterioration in the clinical and laboratory parameters of RA activity.