The aim of the study was to evaluate whether topical application of 0.2% glyceryl trinitrate ointment could reduce post-haemorrhoidectomy healing time and pain both at rest and during defecation. Thirty patients with grade III and IV haemorrhoids were included in the study and divided into two groups. All patients underwent Milligan-Morgan haemorrhoidectomy, and anorectal manometry was performed before surgery and after 5 and 30 days. In one group a placebo ointment was applied to the perianal wounds, while in the other group a 0.2% glyceryl trinitrate ointment was used. Maximum resting pressure was reduced in the glyceryl trinitrate group and increased in the placebo group after 5 days. Postoperative pain both at rest and during defecation, and the time to healing and return to normal activity were significantly reduced in the glyceryl trinitrate group, whilst analgesic consumption was similar. An elevated incidence of headache was observed In the glyceryl trinitrate group. Topical application of glyceryl trinitrate was effective in reducing postoperative pain and healing time, but the substantial incidence of side effects may limit its extensive use.