Introduction. Knowledge of the morphological abnormalities of the atlas (C1) is essential in clinical studies. The complete or partial ossification of the posterior atlanto-occipital ligament, that connects the posterolateral edge of the superior articular facet of the atlas with the superior surface of the posterior arch of C1, is called Kimmerle's anomaly (KA). Clinically KA is associated with Barré-Liéou syndrome, but sometimes, even if present, it can show no symptoms. Aim of the study. Investigation of KA types and their prevalence depending on gender and age of the patient. Materials and methods. This study was carried out on 145 lateral X-rays images of the cervical region of the vertebral column in patients aged between 12-88 years, in some patients KA was present in others absent, and 57 CT 3D reconstructed images of patients only with KA, aged 19-79 years, were examined. The selected images did not contain any other pathological changes of the C1. The data were analyzed by frequency analysis of occurrence and type of KA, logarithmic trend line, Pearson's χ2 test (p-value for the test to be statistically significant is 0.05). Results. On the X-rays images, KA was present in 28.95% of cases. The prevalence of KA among males was 13.1% and in females – 15.85% , that statistically is insignificant (χ2 (2, N=145) = 0.64, p=0.73). On CT 3D reconstructed images, KA in females was established in 56.14% of cases and in males in 43.86% of cases. Considering both imaging studies (99 cases with KA), the prevalence of the complete KA (65.66%) and incomplete (34.34%) was statistically insignificant for both genders (χ2 (1, n=99) = 0.22, p=0.64). The two types of KA can be present at any age independent of gender (all R2 values according to the logarithmic trend line were between 0.01-0.55). The average age for revealed KA was 47.21 years. The morphological structures of KA more detailed were observed on CT 3D reconstructed images, due to the possibility to see: the thickness of the bone bridge, the shape and the dimensions of the foramen, the unilateral, or bilateral position, the starting place of the osteophyte. Conclusions. The presence of KA is relatively common, and it does not depend on age or gender of the patient, having a wide range of morphological variation. Regardless of the type of the anomaly, its presence should be taken into account by medical and non-medical specialists, for the recommendation of an appropriate way of life and treatment. Before surgery on the C1 region, an imaging examination (preferably CT or CT 3D) would help to choose the necessary materials and reduce the risk of damage to the adjacent structures.