The skeletal remains of Giovanna from Austria (1548-1578), first wife of the Grand Duke of Tuscany Francesco I (1541-1587), and their daughter Anna (1569-1584) were exhumed from the Medici Chapels in the Basilica of S. Lorenzo in Florence and submitted to anthropological and paleopathological study. The superior portion of the acetabulum of Giovanna is sloping, and reveals bilateral acetabular dysplasia. The same defect is also present in Anna, together with sacral spina bifida occulta. In both women the anatomical abnormality is limited to a deformation in the roof of both acetabulae and the femoral heads continued to articulate normally within the hip joint. The presence of bilateral acetabular dysplasia in the skeletal remains of Giovanna and her daughter Anna can be explained by a series of risk factors to which the two Medici women were exposed: female sex, practice of swaddling in the first months of life, as well as scoliosis and pelvic deformity for Giovanna and family history for Anna.