The care of patients 65 years or older presents a challenge for evidence-based medicine. Such patients are underrepresented in clinical trials, are more vulnerable to treatment-induced harm, and often are unable to fully participate in treatment decisions. We outline several cautionary themes in the interpretation of clinical studies of therapeutic interventions involving older persons as they apply to processes of everyday clinical decision making. In particular, we focus on issues of study design and quality of evidence, choice of outcome measures, missing outcome data, assessment of potential harm, quantifying treatment effects in individual patients (and adjusting these for effect modifiers and reduced life expectancy), eliciting patient values and preferences, prioritizing therapeutic goals and selection of treatments, and assisting patients in adhering to agreed therapeutic regimens.