Faecal incontinence (FI) is defined as the inability to control bowel movements. The causes of FI are many and diverse. One of the more uncommon reasons for FI is Anorectal Malformations (ARMs). An ARM is a congenital anomaly that affects somewhere between 1/2500 and 1/5000 live born babies. Many ARM patients have persistent FI. Several different procedures have been utilised to address this issue. This thesis aims to evaluate (1) the long-term outcome in adulthood of ARMs in relation to the modern Krickenbeck classification, and (2) scope for treating FI with transanal injection with dextranomer in non-animal stabilised hyaluronic acid (NASHA/Dx), in patients both with and without ARMs. All patients treated for ARMs in Uppsala up to 1993 were invited to participate in a questionnaire study of quality of life and function. The study included 136 patients and compared them with 136 age- and sex-matched controls. The Krickenbeck classification was found to predict functional outcome, and ARM patients had more problems with incontinence and obstipation, as well as inferior Quality of Life (QoL), compared with controls.  Thirty-six patients with FI, owing to causes other than ARMs, were treated with transanal submucous injection of NASHA/Dx. The patients were monitored for two years after treatment. Significant reductions in both their incontinence score and the number of their incontinence episodes were achieved.  A significant improvement in QoL was observed in patients who had at least a 75% reduction in incontinence episodes. No serious complications occurred. A prospective study of transanal injection of NASHA/Dx was conducted on seven patients with persistent FI after ARMs. After six months a significant reduction in the number of incontinence episodes was obtained. A significant improvement in QoL was also found. No serious complications occurred. In conclusion, adult patients with ARMs have inferior outcome of anorectal function and QoL compared with controls. NASHA/Dx is effective and appears to be safe in treating FI in general. This effect seems to be the same in selected patients with persistent FI after ARMs.