This study aimed to assess the relationship between long-term fish consumption and short-term prognosis of patients who had an acute coronary syndrome. The multi-adjusted data analysis from a total of 214 men and 79 women patients showed that intake of fish, n−3 and n−6 fatty acids above 7 portions, 8.8 g and 13.2 g per week correspondingly, is associated with 83%, 83% and 79% reduction on the likelihood of recurrent events in a 30-day period after hospitalisation hospitalization (OR=0.17, 95%CI 0.04–0.80, OR=0.17, 95%CI 0.04–0.81, OR=0.21, 95%CI 0.05–0.97). Conclusively, an inverse relationship between long-term fish and fish oils consumption and short-term prognosis of patients who had had an ACS was observed, irrespective of various potential confounders.