We studied neuroinflammation in individuals with late-life, depression, as arisk factor for dementia, using [11C]PK11195 positron emissiontomography (PET). Five older participants with major depression and 13controls underwent PET and multimodal 3T magnetic resonance imaging (MRI),with blood taken to measure C-reactive protein (CRP). We found significantlyhigher CRP levels in those with late-life depression and raised [11C]PK11195 binding compared with controls in brain regionsassociated with depression, including subgenual anterior cingulate cortex,and significant hippocampal subfield atrophy in cornu ammonis 1 andsubiculum. Our findings suggest neuroinflammation requires furtherinvestigation in late-life depression, both as a possible aetiologicalfactor and a potential therapeutic target.