Peptidyl-prolyl isomerase Pin1 specifically catalyzes the cis/trans-isomerization of proline in the target sequence of phosphorylated Ser/Thr-Pro in over 50 critical regulatory proteins. Pin1 is abnormally overexpressed in a range of human cancers, including lung, breast, colon and prostate cancers. However, few reports of Pin1 overexpression are currently available in clinical samples. Therefore, we examined the expression of Pin1 and p53 in non-pathological human tissues and esophageal cancer tissues. In esophageal cancer tissues, Pin1 and p53 immunoreactivity was detected in cancer cells in 67 and 58% of cases, respectively. Moreover, Pin1 and p53 immunoreactivity was significantly correlated with lymph node-positive disease and more advanced cancer stage. The results demonstrated that high expression levels of Pin1 correlated with high levels of p53. Therefore, Pin1 is suggested to play key roles in the regulation of esophageal cancer.