It was the aim of this single-surgeon series to assess the role of conversion in transanal stapling to techniques and to identify potential factors predictive of conversion. The details of all consecutive patients who were planned for a stapled approach were prospectively recorded in a PC database. Stapling techniques (PPH03, PPH01 and ContourTranstar) were indicated for haemorrhoidal disease and internal rectal prolapse. 'Conversion' from a stapled approach was defined as an unplanned change of the surgical method to a nonstapled, traditional technique, related to indication, anatomy and technical factors. The primary outcomes were whether the procedure was performed using a stapling device only, or whether the procedure was converted. Logistic regression analysis was performed to evaluate multiple variables as potential risk factors for conversion. In a 2-year period (May 2006-May 2008), 258 patients met the inclusion criteria and underwent transanal surgery scheduled as a stapled approach. In these 258 patients, 246 procedures were completed as a stapled procedure [that stapled haemorrhoidopexy, n = 148; stapled mucosectomy, n = 52; stapled transanal rectal resection (STARR) with PPH01, n = 38; and STARR with ContourTranstar, n = 8], giving a completion rate of 95.4%. However, 12 procedures were converted to conventional surgery (including traditional haemorrhoidectomy and the Delorme procedure), giving a conversion rate of 4.6%. The reasons for conversion were related to anatomy and to clinical findings (nonreducible haemorrhoidal prolapse), to new clinical findings not detected preoperatively (proctitis, anal fistula) and to a technical inability to insert the circular anal dilatator because of a deep anal canal. Neither univariate nor multivariate analysis identified any factor to be specifically associated with the risk of conversion. In the era of transanal stapling procedures for haemorrhoids and anorectal prolapse, the majority of procedures can be performed using stapled techniques if strict criteria of indication and patient selection are respected. However, the current study identified a 4.6% conversion rate to traditional treatment, which has an impact on informed consent and requires the surgeon to be familiar with conventional anorectal procedures.