Background and Objectives Physicians routinely discuss adverse effects of medications, but whether discussions match older patients’ desire for information is unexplored. This study compares patient preferences for adverse effect discussions with reported physician practice. Methods Cross-sectional survey of a convenience sample of 100 practicing primary care physicians from 9 medical groups and 178 patients recruited from 11 senior centers in the Los Angeles metropolitan area. Physicians listed the adverse effects they typically discuss when prescribing an ACE inhibitor. Patients were given a hypothetical scenario about a new medication prescription, and were asked to circle the three adverse effects they most wanted to hear about from a list. Results More than 90 % of patients wanted a physician to discuss medication adverse effects: they wanted information about both dangerous (75 % of patients) and common (66 % of patients) adverse effects. However, patients most commonly chose to hear about adverse effects occurring for < 1 % of patients and selected a wide range of adverse effects for discussion. Physicians reported most frequently educating patients about more common and life-threatening adverse effects. Patients who wanted to discuss more adverse effects were more worried about adverse effects than those wishing to hear fewer (4.0 vs. 3.4 on a 5-point Likert scale; p = 0.02). Conclusions For the studied medication, there was little concordance between the medication adverse effects physicians say they discuss and what patients want to hear. Physicians cannot practically verbally satisfy patients’ information desires about the adverse effects of new medications during time-compressed office visits. Innovative solutions are needed.