We aimed to identify the causes and predictors of patient's dissatisfaction after total knee arthroplasty (TKA). Patient's satisfaction was evaluated in 438 TKAs. Causes of patient dissatisfaction were identified using patient interview, physical examinations, laboratory and radiographic tests, and relevant medical consultations. Investigation of 33 dissatisfied knees identified knee-related symptoms in 16 knees (48.5%) and the symptoms unrelated to the replaced knee in 17 knees (51.5%). Multivariate logistic regression analysis revealed that worse preoperative Western Ontario McMaster University Osteoarthritis Index scale pain score and postoperative decrease in range of motion were significantly associated with postoperative dissatisfaction (odds ratio, 7.6 and 2.1, respectively). This study demonstrates that residual symptoms or dysfunctions not directly associated with the replaced knee could be a frequent cause of postoperative dissatisfaction after TKA in osteoarthritic patients.