Peritoneal mesothelioma: an unusual cause of esophageal achalasia. Secondary esophageal achalasia due to malignancy is a rare condition; only 53 such cases have been reported to date. Sixty-two percent of the cases were due to gastric adenocarcinoma. Mesothelioma of the peritoneum is an uncommon neoplasm. The usual presenting symptoms are abdominal pain, abdominal mass, or abdominal distention. The patient we are reporting had peritoneal mesothelioma which presented with dysphagia and weight loss, in addition to the radiological and manometric picture of achalasia. Secondary achalasia was suspected clinically, and was confirmed by computed tomography and laparotomy. The diagnosis of peritoneal mesothelioma was made only by histopathological examination. We are not aware of any other report documenting the association of peritoneal mesothelioma and achalasia. 