Although manometry is used with increasing frequency to evaluate the effectiveness of different treatments for achalasia, the criteria for a successful manometric response have not been well defined. Manometric responses were collected before and after 43 treatments in 35 patients with achalasia in order to determine manometric changes after different clinical outcomes: 15 unsuccessful outcomes and 28 successful outcomes were reported. In the latter, resting pressure of the lower esophageal sphincter decreased to 12.8 mm Hg, whereas in unsuccessful outcomes this was significantly higher (28.2 mm Hg). A decrease of lower esophageal sphincter pressure below 17 mm Hg or more than 40% of the pretreatment level was associated with successful outcomes. Our data suggest that manometry is a good indicator of therapeutic effectiveness and we propose that it be used systematically for objective evaluation of achalasia treatment.