Identifying comorbidities that influence preclinical Alzheimer's disease (AD) can give some insight into the AD early stages trajectories to allow new treatment venues and to guide public health systems to prevent subsequent dementia. To examine the association of multimorbidity with AD neuroimaging markers in cognitively normal older adults. This study had a cross-sectional design. Data regarding 14 comorbidities were obtained for all 318 adults aged 70-85 years, recruited from the community to an ongoing prospective monocentric cohort. They underwent standardized neuropsychological and neuroimaging assessment with automated methods that measured hippocampal volumes, white matter hyperintensity volumes, fluorodeoxyglucose positron emission tomography (FDG-PET) standardized uptake values (SUV) in AD signature regions, and amyloid positron emission tomography (amyloid-PET) SUV ratios. Linear regression was used to assess the association of multimorbidity with AD neuroimaging biomarkers. Multimorbidity is signif icantly associated with lower hippocampal volumes (-0.03 ± 0.01; p = 0.012; R2 = 0.017) and lower FDG-PET SUV (-0.027 ± 0.009; p = 0.005; R2 = 0.022), with no association with amyloid deposition (0.001 ± 0.007; p = 0.884; R2 = 0.0001). Taken individually, obesity and excessive alcohol use are associated with lower FDG-PET values, whereas obstructive sleep apnea and mood disorders are related to lower amyloid-PET SUV ratios. Multimorbidity is associated with preclinical AD imaging markers of neurodegeneration, but not with amyloid.