This paper provides bioarchaeological evidence of Spina Bifida Occulta (SBO) in human skeletons discovered in medieval and post-medieval sites of Eastern Romania and evaluates its prevalence and patterns by examining its relationship to age, sex, type of sites (urban, elite and rural), and its morphological patterns. The skeletons found in burial and reburial tombs from five necropolises of the 14th–19th centuries, discovered in Eastern Romania, were analysed to determine individuals’ age and sex, pathologies and anomalies. Sacral SBO was identified in 11 subjects, for an overall prevalence of 4%; sacral SBO seems to be more common in endogam groups, as it is assumed to be that of the Princely Court. Apparently, this defect is more frequent in men (9 cases were males), its prevalence decreasing with age (from an overall value of 5.47% in young adults to 2.85% in old ones), but no statistically valid association could be demonstrated between the presence/absence of SBO and sex or age. Morphologically, in 8 cases, the sacral SBO corresponded to a more than 50% opening in the posterior arch.