This study examined the frequency of E-cadherin expression in endometrial biopsy or hysterectomy specimens from patients diagnosed with endometrial adenocarcinoma and in normal endometrial tissue specimens. E-cadherin expression was detected by immunohistochemistry using monoclonal antibody to E-cadherin. Specimens were classified as positive when >or= 5% of the tumour cells showed staining for E-cadherin, irrespective of the pattern of staining. Twenty-three endometrioid carcinomas and nine non-endometrioid (four papillary serous and five clear cell) carcinomas were studied, along with 10 normal endometrial tissue specimens as controls. E-cadherin expression was significantly less frequent in non-endometrioid carcinomas compared with endometrioid carcinomas and controls. There was no statistically significant difference in the frequency of E-cadherin expression between endometrioid carcinomas and controls. In conclusion, this study demonstrated that uterine non-endometrioid (papillary serous and clear cell) carcinomas were less likely to express E-cadherin compared with endometrioid carcinomas and normal endometrial tissue. This may help to explain the more aggressive behaviour of non-endometrioid carcinomas.