Introduction: Although the cytological diagnostic criteria for cervical squamous and glandular lesions are established by the Bethesda System for Reporting Cervical Cytology, the reproducibility of the diagnosis of these lesions has been shown to be variable in previous studies. At best, occasional good kappa (κ) values were reached both inter- and intra-observerly. Generally, consensus on high-grade lesions has been better compared to milder changes. Methods: Altogether, 167 conventional Pap smears from 50 patients with histologically confirmed endocervical adenocarcinomas (EAC) and adenocarcinomas in situ (AIS) and from 28 patients with histologically proven high-grade intraepithelial lesions were analyzed by four cytopathologists. Twenty of the smears were later re-evaluated by the same cytopathologists. κ-values between cytopathologists in the categories of squamous versus glandular, negative for intraepithelial lesion or malignancy (NILM), atypical, and preneoplastic/neoplastic were calculated. The diagnostic Pap smears of EAC and AIS with best and worst consensus between observers were then morphologically analyzed. Results: The reproducibility ranged from poor to substantial. The overall κ-values between the four cytopathologists were 0.412, 0.314, 0.272, and 0.082, respectively, in the categories of preneoplastic/neoplastic, squamous versus glandular, NILM, and atypical. Overall intra-observer κ-values were correspondingly 0.491, 0.616, 0.345, and 0.241. In the diagnostic smears of AIS and EAC, the nuclear size >2 times the normal and nuclear pleomorphism were the commonest features associated with good diagnostic consensus and the lack of nuclear enlargement and degenerative changes were associated with poor consensus. Conclusions: The reproducibility of preneoplasia/neoplasia diagnoses was better than that of atypia and NILM both in the inter- and intra-observer part in this study. In the smears from AIS and EAC patients, general neoplasia-associated features were more common in samples with good agreement by the four cytopathologists of the neoplastic nature and the endocervical origin of the lesion.