Sentinel lymph nodes (SLNs) are the first lymph nodes to drain wastes originated from cancerous tissue. There is a need for an in vivo imaging method that can image the intact SLN to further our understanding of its normal as well as abnormal functions. We report the use of ultrahigh sensitive optical microangiography (UHS-OMAG) to image functional microvascular and lymphatic vessel networks that innervate the intact lymph node in mice in vivo. The promising results show a potential role of UHS-OMAG in the future understanding and diagnosis of the SLN involvement in cancer development.