Second-hand smoke (SHS) increases the risk of heart disease by approximately 30% in nonsmokers. Recent evidence from cities that have implemented 100% smoke-free laws has shown that myocardial infarction admissions rapidly declined after law implementation. This decline is, in part, explained by the acute and substantial cardiovascular effects of SHS, many of which are rapid and nearly as large as smoking. The cardiovascular effects of SHS include platelet activation, endothelial dysfunction, inflammation, atherosclerosis development and progression, increased oxidative stress, decreased energy metabolism, and increased insulin resistance. These effects are, on average, 80% to 90% that of chronic active smoking. However, cardiovascular function is partially recovered after SHS exposure ends. Given the evidence, cardiovascular nurses should advise their patients and relatives to avoid SHS exposure and demand smoke-free workplaces and homes.