Although immediate results are good to excellent in great majority of patients who undergo biofeedback treatment (BFT) for chronic constipation and fecal incontinence, they tend to loose the benefit over a period of time. The purpose of this study was to evaluate the long-term sustainability of results after successful biofeedback treatment. Two groups of patients who successfully completed BFT at our institution from 1995 to 1997 were created based on the date of completion. The first had a mean follow-up of 35 months and the second group was followed for an average of 12 months. Both groups were questioned as to the presence of constipation and incontinence. The questioning was focused depending on the patient's diagnosis. This information was then compared with the initial BFT results. Overall, all patients were satisfied by the initial BFT results. All patients initially had an excellent or good response to BFT. However, after a mean of 35 months, in the first group, 19 of 22 patients had a near complete regression back to their pre-biofeedback status. In the 14 patients in the second group with mean follow-up of 12 months, 11 had a significant decay in benefits. Only time was a significant factor in the decay of BFT benefits. In conclusion, BFT is highly effective in the treatment of selected patients with complex defecation disorders. Although there is a high initial success rate, there is a clear loss of the immediate benefits over time. Other factors such as dietary habits, pelvic floor exercises, manometry, invasive EMG, and rectal sensation did not correlate with long-term outcomes. The comparison between the two groups reveals a linear model describing the time decay of the benefits of BFT. Based on the linear model, patients may need reevaluation after one year and may benefit from additional BFT.