A 40 year old man with dysphagia and a giant fibrovascular polyp of the oesophagus is reported. The patient was followed for two years before removal of the polyp. During this period the tumour markedly increased in size and the oesophagus reached a maximum diameter of 5.9 cm. In presence of the polyp the body of the oesophagus had no pressure activity after swallows and a 22 hour intraoesophageal pH record showed pH greater than 7 for 31.4% of the time and never pH less than 4. After excision of the tumour the oesophagus regained normal size and peristalsis. Intraoesophageal pH greater than 7 and less than 4 were recorded for 1.6% and 16.1% of the time respectively. Dysmotility was probably a contributing factor to the genesis of dysphagia induced by the giant fibrovascular polyp. Prolonged alkalinisation of intraoesophageal pH conceivably reflected altered oesophageal clearing of alkaline salivary and/or oesophageal secretions.