BACKGROUND Stabilized non-animal hyaluronic acid/dextranomer (NASHA Dx) gel as injectable bulking therapy has been shown to decrease symptoms of faecal incontinence, but the durability of treatment and effects and influence on quality of life (QoL) is not known. The aim of this study was to assess the effects on continence and QoL and to evaluate the relationship between QoL and efficacy up to 2 years after treatment. METHODS Thirty-four patients (5 males, mean age 61, range 34-80) were injected with 4 × 1 ml NASHA Dx in the submucosal layer. The patients were followed for 2 years with registration of incontinence episodes, bowel function and QoL questionnaires. RESULTS Twenty-six patients reported sustained improvement after 24 months. The median number of incontinence episodes before treatment was 22 and decreased to 10 at 12 months (P = 0.0004) and to 7 at 24 months (P = 0.0026). The corresponding Miller incontinence scores were 14, 11 (P = 0.0078) and 10.5 (P = 0.0003), respectively. There was a clear correlation between the decrease in the number of leak episodes and the increase in the SF-36 Physical Function score but only patients with more than 75 % improvement in the number of incontinence episodes had a significant improvement in QoL at 24 months. CONCLUSIONS Anorectal injection of NASHA Dx gel induces improvement of incontinence symptoms for at least 2 years. The treatment has a potential to improve QoL. A 75 % decrease in incontinence episodes may be a more accurate threshold to indicate a successful incontinence treatment than the more commonly used 50 %.