We aimed to test the hypothesis that the effect of chronic pain on depressive symptoms is mediated through hippocampal volume (HV). Participants were 131 non-demented adults over the age of 70 years from the Einstein Aging Study. Smaller right and left HV were both associated with higher depressive symptoms, but only smaller right HV was associated with chronic pain. In mediation models, right HV was a significant mediator for the effect of chronic pain on depression. Our findings suggest presence of a shared brain substrates between chronic pain and depression as reflected by right HV.