The reliability of histological diagnosis of squamous epithelial changes was tested by letting 13 pathologists read 1,001 consecutive cervical biopsies twice. Intra‐observer and inter‐observer agreement, variance, and deviation of diagnosis were determined. The diagnostic ability showed great individual variation and no significant correlation to experience in pathology. The diagnosis of invasive cancer had a high diagnostic specificity, and the diagnostic sensitivity of the diagnosis of no significant epithelial changes was high too. The reliability of the diagnosis of dysplasia and carcinoma in situ proved unsatisfactory.