We examined the T1w/T2w ratio of MR images in cognitively normal elderly subjects. Aβ deposition was quantified by [11C] PiB-PET binding potential (PiB-BPND). The T1w/T2w ratios were positively correlated with PiB-BPND values. We correctly discriminated subjects with high PIB-BPND using the T1w/T2w ratio. The T1w/T2w ratio from MRI is a potential biological marker of early Aβ deposition.