Objective To investigate the relationship between imaging properties of hypertrophic olivary degeneration (HOD) and its underlying pathologic mechanism, thus to enhance the cognition and clinical diagnosis performance. Methods 6 clinically and radiologically diagnosed cases of HOD were retrospectively observed according to their clinical features and MRI findings. Review the literature to analyze the corresponding clinical manifestations, MRI findings and pathologic mechanism. Results HOD was observed ipsilaterally with primary lesions when unilateral pontine central tegment tract was involved (2 cases) and unilateral pontine central tegment tract and contralateral dentate nucleus were both involved (1 case), while bilaterally when primary lesions involved unilateral superior cerebellar peduncle (1 case). Primary lesions of 2 cases involved bilateral pontine central tegment tract, one was observed bilateral HOD while the other unilaterally. All the 6 cases manifested as enlargement of ventral lateral part of medulla. The lesions presented hyper-intensity signal on T2weighted images and fluid-attenuated inversion-recovery (FLAIR) images. The T1weighted images revealed iso-intensity signal in 5 cases and slightly high signal in 1 case. Conclusion HOD has specific clinical and radiological features and usually occurs in particular anatomical sites. Correct diagnosis could be made if the primary lesions are taken into consideration.