Background: Intrasphincteric injection of botulinum toxin has been reported as a safe and effective alternative treatment in oesophageal achalasia, especially in high‐risk and elderly patients.Aim: To compare two formulations of botulinum toxin in the management of achalasia.Patients and methods: We randomly compared the efficacy and safety of 100 U of Botox (Allergan, Irvine, USA) and 250 U of Dysport (Ipsen, Milan, Italy), injected through a sclerotherapy needle at the level of the lower oesophageal sphincter, in 78 consecutive patients with achalasia. Symptom score, oesophageal manometry and 24 h pH‐metry were recorded (before and 1 month after therapy). Symptom score was also obtained 6 months after treatment.Results: One month after treatment, the effects of the toxin on symptoms and oesophageal tests were similar for both formulations. Lower oesophageal sphincter pressure decreased from 31 ± 12 to 18 ± 5 mmHg after Botox, and from 35 ± 9 to 18 ± 10 after Dysport. At the end of the follow‐up period (6 months), symptom score decreased from 5 ± 1.2 to 1.2 ± 0.8 after Botox and from 5.2 ± 1.5 to 1.5 ± 1 after Dysport. Moreover, the percentages of patients who failed to respond to treatment (10% and 17.5%) and who relapsed during follow‐up (12% and 24%) did not differ significantly. No patient complained of reflux symptoms after treatment, although abnormal acid exposure was documented in two subjects.Conclusions: Both formulations of botulinum toxin have comparable efficacy in the treatment of oesophageal achalasia, for up to 6 months of follow‐up.