BACKGROUND Mortality due to coronary heart disease has been declining as a result of better clinical patient management, including secondary prevention with the aid of effective drugs. The clinical challenge remains how to improve adherence to evidence-based cardiac care for all patients who can benefit from it. The present study aimed to assess the effectiveness of drug use after acute myocardial infarction (AMI) in reducing total medium-term mortality and to establish whether there are disparities in prescribing all therapies of demonstrated effectiveness. DESIGN We conducted a retrospective cohort study between 2002 and 2009 using a record linkage database, considering 1327 patients discharged after AMI. METHODS Cox's regression models were used for the survival analysis with time-dependent variables. Logistic regression analyses were performed to investigate the inequalities in the actual use of therapies found significantly associated with a lower mortality in the survival analyses. RESULTS Therapies independently associated with a lower all-cause mortality risk were antiplatelet drugs, beta-blockers, angiotensin-converting enzyme inhibitors, and statins. Gender-related differences in prescriptions were seen for statins and antiplatelet drugs; age-related differences emerged for all drugs. Associated chronic obstructive pulmonary disease reduced the likelihood of patients taking the effective treatments. CONCLUSION The present study revealed disparities in the use of treatments for the secondary prevention of coronary heart disease unjustifiable on the strength of clinical evidence.