Background: Intersphincteric injection of botulinum toxin (BoTx) has demonstrated to be effective in the short-term treatment of achalasia. Aim: To assess the efficacy, safety and long-term outcome of BoTx injection into the lower esophageal sphincter (LES) of patients with achalasia. Patients and methods: Eight patients received 80 units of BoTx. Assessment of response was based on changes in the symptom scores (0-9) and esophageal manometric studies. Results: Six out of 8 patients (75%) had sustained clinical improvement after therapy. This effect was maintained for a mean time of 17.8 months. The symptom score decreased from a mean of 6,7 to 0,5 (p < 0.01) and after treatment, LES pressure decreased from 63 to 25.5 mm Hg (p = 0.07). There were no serious adverse effects. Five of the six responders have relapsed. Two of these patients received a second BoTx injection with satisfactory results, two went to surgery and one refused other type of therapy and died of pneumonia. Conclusions: Intersphincteric BoTx injection is a simple, safe and effective method of treatment in patients with achalasia, with a duration of response averaging 1,5 years. Its use may be suggested in some patients with high surgical risk and those who refuse a more invasive therapy. It is also useful in malnourished patients to attain an adequate nutritional status before surgery.