There are several important issues regarding the manner in which medications are tested prior to their release and monitored after approval that must be appreciated in considering issues related to cardiovascular safety of medication treatments for attention-deficit/hyperactivity disorder (ADHD) in adults. First, patients treated in clinical trials are not necessarily representative of those seen in practice settings, as specific inclusion/exclusion criteria in studies limit a variety of psychiatric, medical, and social factors that could potentially introduce confounds related to the collection and/or interpretation of efficacy, tolerability, and safety data. However, many of these factors are present in patients treated in clinical practice. In addition, the manner in which medications are administered in clinical trials does not necessarily replicate the way they are used in the community. Often, there are differences in titration schemes and dosing options. Also, in clinical trials, drugs are rarely studied in combination, although they are often used in this manner in practice settings. Further, Phase III clinical trials (at least in psychiatry) often do not enroll a large enough sample to evaluate infrequently occurring adverse events. Rather, the predominance of information regarding rare side effects is derived from voluntary reports made after a drug comes to market—and therefore likely under-reports the phenomenon. Finally, information regarding drug safety that comes to practitioners in the form of medication warnings or advisories may reflect concerns that extend beyond the strict interpretation of clinical trials data. These and other issues represent major obstacles in attempting to fully understand issues related to safety and tolerability of medication in “real world” settings.