Maximal exercise testing is associated with a low but finite incidence of cardiac arrest, AMI, and even death. Pharmaco- logical stress agents fall into 2 broad categories: beta-agonists such as dobutamine, which increase heart rate and inotropy, and vasodilators such as adenosine, dipyridamole, or regade- noson, which act to increase blood flow to normal arteries while decreasing perfusion to stenotic vessels. Each of these pharmacological stress agents also carries a very small risk of drug-specific adverse events (dobutamine: ventricular ar- rhythmias; dipyridamole/adenosine: bronchospasm in chronic obstructive pulmonary disease). Nuclear perfusion imaging and CCTA use ionizing radia- tion techniques for visualizing myocardial perfusion and anatomic CAD, respectively. Risk projections are based largely on observations from atomic bomb survivors exposed to higher levels of ionizing radiation. The Linear-No- Threshold hypothesis states that any exposure could result in an increased projected cancer risk and that there is a dose response relationship to elevated cancer risk with higher exposures. Considerable controversy exists surrounding the extrapolation of projected cancer risk to low-level exposure in medical testing, and no reported evidence links low-level exposure to observed cancer risk. Even when the Linear-No- Threshold hypothesis is used, the projected incident cancer is estimated to be very low for nuclear MPI and CCTA.93 95 Nevertheless, general agreement exists that the overriding principle of caution and safety should apply by projecting the Linear-No-Threshold hypothesis. The principle of As Low as Reasonably Achievable (ALARA) should be applied in all patient populations. 