Recent trials show that absolute risk for ASCVD events typically exceeds that of bleed- ing and, although the gap of relative benefit to relative harm for aspirin has narrowed, the num- ber needed to treat to prevent an ASCVD event remains lower than the number needed to harm to cause bleeding. Others may feel that the ben- efit of prophylactic aspirin is comparable to the risk and may instead choose to focus on optimal control of other modifiable ASCVD risk factors. Therefore, a Class IIb recommendation remains more suitable than a Class III recommendation for adults 40 to 70 years of age. Given the nar- row overall balance between benefits and harms of prophylactic aspirin, there is limited justifica- tion to use aspirin at doses >100 mg daily for pri- mary prevention. Indeed, meta-analyses suggest that the ASCVD risk benefit for low-dose aspirin is equivalent to that for high-dose aspirin, but the bleeding risk is higher with high-dose aspi- rin. Recent observational studies motivate future research on the personalization of prophylactic aspirin dose according to patient-specific factors though we note that, regarding weight specifically, there was no evidence low- dose aspirin was any more effective in low-weight individuals than in high-weight individuals in the more recently published ASCEND (A Study of Cardiovascular Events iN Diabetes) trial,S4.6-16 trial. Most importantly, recent clinical trials also teach us that low-dose prophylactic aspirin may be best justified among persons at high ASCVD risk who cannot achieve optimal control of other ASCVD 2. 