Cognitive pharmacy trials seek to identify interventions that benefit patients. The potential benefits of an intervention are primarily evaluated by outcome measures. The question then is: What is the optimal outcome measure? Unfortunately, the question remains unsolved. Several factors must be taken into consideration when conducting outcome research—particularly within cognitive pharmacy trials. The interventions are often complex and non-specific, and seek to improve symptom control, optimise the use of medications and reduce medication-related risks. “Hard” endpoints, such as mortality and hospital admissions, may not be the optimal outcome measures, since cognitive pharmacy interventions are unlikely to result in changes in these measures. Instead, adverse drug events or “soft” endpoints, such as quality of life, drug-related problems and patient satisfaction may be appropriate choices of outcome measures. Finally, it is not only outcome measures that may pose a challenge when conducting outcome research; other essential components include study design, type of intervention, the patient population, etc.