Patients with longstanding achalasia have an increased risk of developing esophageal cancer. Surveillance is hampered by chronic stasis. We investigated whether aberrant expressions of tumor suppressor gene p53 and proliferation marker ki67 are early predictors for progression to malignancy. In 399 achalasia patients, 4% died of esophageal cancer despite surveillance. We performed a cohort study, using surveillance biopsies from 18 patients (11 carcinoma, one high-grade dysplasia [HGD], and six low-grade dysplasia [LGD]) and 10 controls (achalasia patients without cancer or dysplasia development). One hundred sixty-four biopsies were re-evaluated and studied for p53 and ki67 expression using immunohistochemistry. Eighty-two percent of patients with cancer/HGD showed p53 overexpression in surveillance biopsies at a mean of 6 (1-11) years prior to cancer development. In 67% of patients with LGD and only in 10% of the controls p53 overexpression was present. The proportion of samples with p53 overexpression increased with increasing grades of dysplasia. We found no difference for ki67 overexpression. p53 overexpression may identify achalasia patients at increased risk of developing esophageal carcinoma. Further study is needed to determine if patients with p53 overexpression would benefit from intensive surveillance to detect esophageal neoplasia at a potential curable stage.