An assessment of the presence and patterns of porotic hyperostosis and periosteal reactions in the skeletal population (n = 1,014) from St. Helen-on-the-Walls, York, are used to examine health and disease in urban medieval England. The analyses of these two lesions indicate that 58% of the population display evidence of porotic hyperostosis and that 21.5% of the population display periosteal reactions. Through differential diagnosis it is asserted that porotic hyperostosis is associated with iron-deficiency anemia, and that periosteal reactions may be the result of endemic treponematosis and/or non-specific infection, including parasitic infestation. An association between the presence of remodeled lesions and adulthood is noticeable for both porotic hyperostosis and periosteal reactions, as is a pattern of increased average age at death for those displaying both conditions.