Health care workers’ perceptions of patient suffering have not been well studied. Patients and health care workers were invited to answer a single, open-ended question. To develop a survey tool that could be validated and used for future research, what health care workers thought causes or caused the most suffering for patients was compared with what patients actually identified as the cause of their worst suffering. Health care workers underestimated loss and significantly underestimated physical nonpainful symptoms as causes of maximal suffering. Communication, emotional, and systems issues were often overestimated by health care workers. Health care workers may not accurately perceive what causes the worst suffering for patients. More studies are needed.