BACKGROUND: Previous research has shown a socioeconomic status (SES) gradient in the receipt of cardiac services following acute myocardial infarction (AMI), but much less is known about SES and the use of secondary preventive medicines following AMI. OBJECTIVES: To examine the role of income in initiation of treatment with ACE-inhibitors, beta-blockers and statins in the 120 days following discharge from hospital for first AMI. DESIGN: A cross-sectional study with a population-based cohort. PARTICIPANTS: First-time AMI patients between age 40 and 100 discharged alive from the hospital and surviving at least 120 days following discharge between January 1, 1999 and September 3, 2006. MAIN MEASURES: Binary variables indicating whether the patient had filled at least one prescription for each of the medicines of interest. KEY RESULTS: Our results reveal a significant and positive income gradient with initiation of the guideline-recommended medicines among male AMI patients. Men in the third income quintile and above were significantly more likely to initiate treatment with any of the medicines than those in the first quintile, with those in the fifth income quintile having 37%, 50% and 71% higher odds of initiating ACE-inhibitors, beta-blockers and statins, respectively, than men in the lowest income quintile [OR = 1.37 95% CI (1.24, 1.51); OR = 1.50 95% CI (1.35, 1.68); and OR = 1.71 95% CI (1.53, 190)]. The gradient was not present among women, although women in the fifth income quintile were more likely to initiate beta-blockers and statins than women in the lowest income quintile [OR = 1.25 95% CI (1.06, 1.47) and OR = 1.32 95% CI (1.12, 1.54)]. CONCLUSIONS: There were inequities in treatment following AMI in the form of a clear and often significant gradient between income and initiation of evidence-based pharmacologic therapies among male patients. This gradient persisted despite significant changes in coverage levels for the costs of these medicines.