Human Factors and Ergonomics (HFE) has the potential to transform the lives of older adults by helping them better manage their health and disease. Older adults are often beset with multiple chronic illnesses and struggle to manage complex medication regimens. Non-adherence, errors, and poor outcomes are common. New research shows that patients’ health-related activities constitute an effortful, goal-driven type of work called patient work. HFE can play a major role in the study and improvement of patient work performance but current HFE methods are not fully suitable. This is in part because patient work is variable and takes place in home and community settings dissimilar to those commonly studied by healthcare HFE researchers. The objective of this study was to perform a work systems analysis of the medication management work of older adults with heart failure by adapting a method more suitable for the study of patient work. This qualitative longitudinal study used an innovative digital diary data collection method. Fifteen older adults with heart failure made medication-related multimedia recordings over a one-week period followed by an interview. These data were content analyzed according to the Patient Work System model. Results identified 6 organizational (70 instances), 7 task (45 instances), 7 tool (31 instances), 6 patient (31 instances), 4 social (21 instances), and 2 physical work system factors (10 instances). Patient medication performance suffered from a lack of care coordination and integration. Organizational tools such as mail order delivery facilitated access, but many patients devised tools and strategies to address other barriers. The study concluded that there is a need to design task-relevant tools to support and optimize the patients’ medication management work systems.