BACKGROUND: Despite the well-documented relationship between lobar cerebral microbleeds (lCMB) and Alzheimer's disease (AD), there is limited knowledge about the role of lCMB in AD pathology. OBJECTIVE: To understand the nature of this relationship, we investigated the association between lCMB, amyloid load, perfusion, and metabolism. METHODS: Participants with AD, mild cognitive impairment (MCI), and healthy controls were recruited and scanned with 11C-Pittsburg-Compound B (PiB), Fluorodeoxyglucose (FDG) PET, and susceptibility-weighted MRI. Early PiB-PET frames were used to estimate perfusion. The association between lCMB and PET uptake in each anatomical lobe was measured using multiple regression models. RESULTS: The presence of lCMB predicted increased total (p < 0.001) and regional (p = 0.0002) PiB uptake, as well as decreased cerebral perfusion (p = 0.03). Cases with lCMB had hypometabolism in their temporal lobe (p = 0.04). CONCLUSION: There are significant relationships between lCMBs and various markers of AD pathology. lCMB has a spatial association with Aβ load and a complex effect on perfusion and metabolism.