A spectral/Fourier domain optical coherence tomography (OCT) intravital microscope using a supercontinuum light source at 1.7 μm was developed to study subcortical structures noninvasively in the living mouse brain. The benefits of 1.7 μm for deep tissue brain imaging are demonstrated by quantitatively comparing OCT signal attenuation characteristics of cortical tissue across visible and near-infrared wavelengths. Imaging of hippocampal tissue architecture and white matter microvasculature are demonstrated in vivo through thinned-skull, glass coverslip-reinforced cranial windows in mice. Applications of this novel platform include monitoring disease progression and pathophysiology in rodent models of Alzheimer's disease and subcortical dementias, including vascular dementia.