Objective: The aim of the presented study was to compare the diagnostic procedures palpation, sonography and endoscopy for detection of lesions of the inner mucosal layer in bovine teats and to evaluate their diagnostic value. Material and methods: The investigation material involved 436 teats of 109 dairy cows of different breeds which were slaughtered out of different reasons. All teats were examined by palpation, sonography and endoscopy via papillar duct for the presence of teat cistern mucosa lesions. Afterwards teats were opened by longitudinal incision for macroscopic evaluation. Tissue samples of obvious lesions were taken and prepared for histopathological examination. Based on the results of macroscopic and histopathological investigations the results of the different diagnostic procedures were compared. Results: In 38 cases (8.7%) remarkable findings were present in the macroscopic investigation, which had only been detected without exception by endoscopy via teat canal. Both other diagnostic methods dropped in their results in contrast to this clearly. Endoscopy (p <= 0.001) and sonography (p <= 0.0001) proved to be of significant higher diagnostic impact than palpation. A significant difference between the results of endoscopy and sonography could not be detected (p >= 0.05). Histopathological findings reflected the results of the palpatoric, sonographic and endoscopic investigation in a high amount. Conclusions and clinical relevance: Alterations of the teat cistern mucosa of dairy cows are insufficiently detected by use of classical clinical method palpation. Imaging diagnostic procedures (sonography/endoscopy) extend the diagnostic spectrum substantially. Sonography is usually sufficient when lesions are located in the teat cistern. However, in case of alterations at the inner orifice of the papillar duct or the papillar duct itself an additional endoscopic examination is recommended for definition of a suitable therapy method.