To compare the clinical and functional results after open and closed haemorrhoidectomy with or without internal sphincterotomy, 55 patients were randomised into two groups: 29 had Milligan-Morgan (MM) and 26 had Ferguson (F) operations. Internal sphincterotomy was carried out in 14 cases with high anal pressures (7 MM, 7 F). Anal manometry and anal ultrasound were performed prior and after surgery. Postoperative pain was evaluated by a 1–10 visual analogue scale. Urinary retention, faecal impaction, bleeding, anal fissures, sepsis, strictures, tags, incontinence and recurrence of piles were prospectively evaluated. The groups were homogeneous in terms of age, gender and duration of follow-up. The mean postoperative pain score was 2.3 after MM and 2.9 after F. Urinary retention rate was 10.3% after MM and 3.8% after F, while severe bleeding rate was 3.4% and 0, respectively. No sepsis, fissure or faecal incontinence occurred in either group. Mild anal strictures were 13.3% (MM) and 3.9% (F), while anal tags due to major wound dehiscence and requiring ambulatory excision were 0 (MM) and 7.7% (F). One patient in either group had a recurrence of piles. Anal resting pressure decreased postoperatively to 51.5 ± 9.2 (MM) and 52.1 ± 14.9 mm Hg (F). Postoperative internal sphincter thickness was 2.1 ± 0.3 (MM) and 2.9 ± 1.7 mm (F). All differences were not statistically significant. Even if bleeding and anal stricture occurred more frequently following MM and anal tags were more frequent after F, no significant difference was found between open and closed haemorrhoidectomy in terms of morbidity rate. Both techniques caused low postoperative pain, with good anal continence and good chance of cure. Internal sphincterotomy did not significantly decrease postoperative pain, did not cause faecal soiling and was rarely followed by anal stricture.