Unique drug responses that may result in adverse events are among the ethnocultural differences described by the Agency for Healthcare Research and Quality. These differences, often attributed to a lack of adherence on the part of the older adult, may be linked to genetic variations that influence drug responses in different ethnic groups. The paucity of research coupled with a lack of knowledge among health care providers compound the problem, contributing to further disparities, especially in this era of personalized medicine and pharmacogenomics. This article examines how age-related changes and genetic differences influence variations in drug responses among older adults in unique ethnocultural groups. The article starts with an overview of age-related changes and ethnopharmacology, moves to describing genetic differences that affect drug responses, with a focus on medications commonly prescribed for older adults, and ends with application of these issues to culturally congruent health care.