Objective: In this study, we aimed to retrospectively investigate and confirm whether atypical nuclear findings in endometrial cytology are useful when assessed by image morphometry in liquid-based cytology (LBC) and compared with microscopic evaluation. Methods: In total, 53 cases were selected for this study, including 11 presenting proliferative endometrium, 12 with surface papillary syncytial change with endometrial glandular and stromal breakdown (EGBD-SPSC), 10 endometrioid carcinoma grade 1 (G1-EEC), 10 EEC grade 3 (G3-EEC), and 10 endometrial serous carcinomas (ESC). Nuclear image morphometry for nuclear geometric features (area, grey value, aspect ratio, internuclear distance, nucleolar diameter) was performed using ImageJ computer software. For assessing nucleoli, 3861 nuclei were measured, and for nuclear findings, except for nucleoli, 4036 nuclei were measured in total. Results: (a) Compared with G1-EEC, G3-EEC and ESC presented a marked increase in all six parameters (nuclear enlargement, anisonucleosis, nuclear shade, nuclear shape, irregularity of nuclear arrangement, and nucleolar size). (b) EGBD-SPSC presented a marked increase in two parameters (nuclear shade, nuclear shape) when compared with G1/G3-EEC and ESC. (c) Compared with EGBD-SPSC, EEC and ESC demonstrated a marked increase in nucleolar size (≥2.0 μm). (d) ESC presented a marked increase in nucleolar size (≥3.0 μm) when compared with G3-EEC. Conclusions: Here we confirmed that atypical nuclear findings evaluated by image morphometry are as useful as microscopic evaluations in endometrial cytology. We believe that the objective evaluation of nucleolar size could contribute to an accurate diagnosis of endometrial-LBC samples.