Spontaneous perforation of the oesophagus is a rare occurrence that is usually due to vomiting and is seldom associated with an oesophageal lesion. We report a case of the spontaneous perforation of a large oesophageal diverticulum not preceded by any precipitating event in a 75-year-old male who was not known to have achalasia. The diverticulum was repaired by emergency surgery. Achalasia was later diagnosed and successfully treated with botulin toxin injection. Surgery decision-making and the treatment of achalasia are discussed.