['Over the last few years, there has been increasing attention on surgical procedures to treat haemorrhoids. The Milligan-Morgan haemorrhoidectomy is still one of the most popular surgical treatments of haemorrhoids. The aim of the present work is to assess postoperative pain, together with other early and late complications, after Milligan-Morgan haemorrhoidectomy as we could observe in our experience before and after performing an internal sphincterotomy.', 'from January 1980 to May 2007, we operated 850 patients, but only 699 patients (median age 53) were included in the present study because they satisfied our inclusion criteria. The patients were divided into two groups: all the patients operated on before 1995 (group A); all the patients operated on after 1995 (group B). Since 1995 an internal sphincterotomy of about 1 cm has been performed at the end of the procedure. The data concerning the complications of these two groups were compared. All the patients received a check-up at one and six months after operation and a telephone questionnaire three years after operation to evalue medium and long term results.', 'after one month 507 patients (72.5%) did not have any postoperative complication. Only 192 patients (27.46%) out of 699 presented postoperative complication and the most frequent one (23.03%) was pain. The number of patients who suffered from postoperative pain decreased significantly when performing internal sphincterotomy, going from 28.8% down to 10.45% (chi(2): 10,880; p = 0,0001); 95% Confidence Interval (CI) 24.7 to 28.9 (group A) and 10.17 to 10.72 (group B). In 51 cases (7.29%) urinary retention was registered. Six cases of bleeding (0.85%) were registered. Medium and long term follow up did not show any difference among the two groups.'] Does internal sphincterotomy reduce postoperative pain after Milligan Morgan haemorrhoidectomy?