Chronic coronary artery disease (CAD) and peripheral artery disease (PAD) are both associated with elevated risks of major adverse cardiovascular events (MACE) and major adverse limb events (MALE). The frequency of these events in patients with CAD or PAD, and their corresponding costs, are not well understood. Accordingly, we describe the incidence and cost of both MACE and MALE in patients with CAD or PAD. Using a database that included healthcare claims linked to electronic medical records, we identified patients with evidence of chronic CAD and PAD, respectively, between January 1, 2009, and September 30, 2016. We assessed the occurrence of MACE (defined as myocardial infarction, stroke, or cardiovascular-related death) and MALE (critical limb ischemia, amputation, or peripheral artery disease-related revascularization). A total of 99,730 patients met all selection criteria: 86.0% had CAD, 25.8% had PAD, and 11.8% had both. Mean (±standard deviation) age was 67.7 (±11.5) years and 59.8% were male. During follow-up (mean: 1.8 years), 13.6% experienced MACE or MALE (6.3 per 100 person-years [PYs]), predominantly MACE (9.6% [4.3 per 100 PYs]). Adjusted 1-year healthcare costs were $44,495 greater in patients who experienced MACE or MALE (mean [95% confidence interval]: $64,099 [$33,254 to $123,557] vs $19,604 [$10,175 to $37,771]; p < 0.001). In conclusion, approximately 1 in 7 patients with chronic CAD or PAD experiences additional MACE or MALE within approximately 2 years of follow-up; the relatively high risk and cost of these events highlight the need for new secondary prevention therapies that may improve outcomes in these patients.