Background: Total knee arthroplasty is a common procedure with generally good results. However, there are still patients who are dissatisfied without known explanation. Satisfaction and dissatisfaction have previously been captured by quantitative designs, but there is a lack of qualitative studies regarding these patients' experiences. Qualitative knowledge might be useful in creating strategies to decrease the dissatisfaction rate. Methods: Of the 348 patients who responded to a letter asking if they were satisfied or dissatisfied with their surgery, 61 (18%) reported discontent. After excluding patients with documented complications and those who declined to participate, semi-structured interviews were conducted with 44 patients. The interviews were analyzed according to qualitative content analysis. The purpose was to describe patients' experiences of discontentment 1 year after total knee arthroplasty. Results: The patients experienced unfulfilled expectations and needs regarding unresolved and new problems, limited independence, and lacking of relational supports. They were bothered by pain and stiffness, and worried that changes were complications as a result of surgery. They described inability to perform daily activities and valued activities. They also felt a lack of relational supports, and a lack of respect and continuity, support from health care, and information adapted to their needs. Conclusion: Patient expectation seems to be the major contributing factor in patient discontentment after knee replacement surgery. This qualitative study sheds light on the on the meaning of unfulfilled expectations, in contrast to previous quantitative studies. The elements of unfulfilled expectations need to be dealt with both on the individual staff level and on the organizational level. For instance, increased continuity of healthcare staff and facilities may help to improve patient satisfaction after surgery.