People with high intake of fish have lower reported rates of depression and a small trial in psychiatric patients suggested that fish oil supplements reduced episodes of depression and mania. As part of a factorial trial of interventions to reduce mortality in angina 452 men were randomised to advice to eat more fatty fish or no fish advice. Maxepa fish oil capsules were supplied to men who found the fish unpalatable. Fish intake and mood were assessed at baseline and six months. Most men (83%) had mood assessed using the Derogatis Stress Profile at baseline and follow-up. Self reported intake of fish was higher in the fish advice group at six months. There was, however, no difference in depression or anxiety in those allocated to receive fish advice. After controlling for baseline mood, the difference in depression score between those randomised to fish advice and those not was 1.29 (95% CI -0.29 to 2.88) and the difference in anxiety was 0.82 (95% CI -0.57 to 2.22) with positive differences indicating more depression or anxiety in those allocated to the fish arm. This trial provides no evidence that increased fatty fish intake in people without depressive symptoms has any substantial effect on mood.