Achalasia of the esophagus is presumed by many to be a premalignant lesion leading to an increased risk of squamous cell carcinoma. There is disagreement, however, as to the precise risk of malignant degeneration and there is no consensus as to either the need for close surveillance of achalasia patients or the surveillance technique that should be employed. A review of the available literature on the subject has disclosed a wide range of reported cancer risks in achalasia patients, from zero to 33 times that of the normal population. Cancers, when discovered, are often unresectable and the median survival when they are resectable is low. A personal experience with 241 achalasia patients treated during the past quarter of a century disclosed that 9 had carcinoma, for a prevalence of 3.7%. Carcinoma developed in 3 of these 9 while they were under our observation. This translates into one cancer per 1,138 patient-years of follow-up, an incidence of 88 per 100,000 population, and a risk 14.5 times that of the age-adjusted and sex-adjusted general population. Because of the low postresection survival rate if treatment is delayed until carcinoma of the esophagus becomes symptomatic, closer surveillance of achalasia patients is recommended than has been the case. Because it seems unlikely that close endoscopic surveillance will prove to be cost-effective, periodic (every 2 to 3 years) blind brush biopsy warrants further study as a means of surveillance.