Dysphagia following fundoplication: "slipped" fundoplication versus achalasia complicated by fundoplication. Failure to obtain preoperative esophageal manometry in patients being considered for antireflux surgery can result in immediate persistent postoperative dysphagia due to a missed diagnosis of achalasia. We describe the clinical assessment and management of a case of delayed postoperative dysphagia due to a "slipped" fundoplication, which is contrasted with three patients with immediate postoperative dysphagia due to a missed diagnosis of achalasia. Surgical revision was required to correct the "slipped" fundoplication, and pneumatic dilatation was successfully used in two of three cases of achalasia complicated by fundoplication. Careful preoperative esophageal evaluation with manometry is essential to rule out the presence of a primary esophageal motor disorder. 