['The aim of the study was to identify variables affecting the outcome of transanal advancement flap repair (TAFR) for perianal fistulas of cryptoglandular origin.', "Between 1995 and 2000, a consecutive series of 105 patients (65 women, 40 men), with a median age of 44 (range 19-72) years was included in the study. The patients were recruited from the colorectal departments of two university medical centres. Patients with a rectovaginal fistula and those with a fistula due to Crohn's disease were excluded. The following variables were assessed: age, sex, number of previous attempts at repair, preoperative seton drainage, fistula type, presence of horseshoe extensions, location of the internal opening, postoperative drainage, body mass index and the number of cigarettes smoked per day. The results were analysed by means of multiple logistic regression.", 'The median follow-up was 14 months. No differences were observed between the two centres. TAFR was successful in 72 patients (69 per cent). None of the variables affected the outcome of the procedure, except for smoking habit of the patient. In patients who smoked the observed healing rate was 60 per cent, whereas a rate of 79 per cent was found in patients who did not smoke. This difference was statistically significant (P = 0.037). Moreover, a significant correlation was observed between the number of cigarettes smoked per day and the healing rate (P = 0.003).'] Does smoking affect the outcome of transanal mucosal advancement flap repair of trans-sphincteric fistulas?