Biofeedback therapy has been widely used for the treatment of constipated patients. However, there are only a few reports about the clinical factors that can predict the effectiveness of biofeedback therapy. The aim of this study was to evaluate prognostic factors before the initiation of biofeedback treatment in constipated patients. Biofeedback treatment was performed in 114 patients with constipation. After classifying the patients into two groups, responder and non-responder by subjective and objective parameters, univariate and multivariate analysis were performed to evaluate the factors associated with effectiveness of biofeedback therapy. Eighty-five patients (74.6%) responded to biofeedback therapy. Pre-treatment balloon expulsion test, paradoxical contraction on manometry, defecation index and anal residual pressure during straining were the factors that influenced the results of biofeedback treatment. On multivariate analysis, defecation index (odds ratio=67.5, p<0.05) and paradoxical contraction on manometry (odds ratio=0.053, p<0.05) were the factors that showed significant difference between the responders and non-responders. This study suggests that several pre-treatment prognostic factors are associated with response to biofeedback for the constipated patients. Using prognostic factors, we may be able to evaluate the patterns of pelvic floor dysfunction and responsiveness of biofeedback therapy for the patients with constipation.