We review methods applied to imaging and assessment of the microcirculation and document the recent progress. Visible and near-infrared light, particularly in the wavelength region of 600 nm to 1100 nm, offer a window into human and animal tissues due to reduced scattering and absorption. Laser Doppler perfusion imaging (LDPI) and laser speckle perfusion imaging (LSPI) are used in the non-invasive investigation of the microcirculation. This paper compares the two techniques with the recently developed Tissue Viability (TiVi) imaging system, which is proposed as a useful tool to quantify red blood cell concentration in the microcirculation. Both imaging and point scanning by the devices were used to quantify microvascular reactivity. The responses can be explained by physiological understanding and subtle differences by technophysiological knowledge. The resolution, penetration depth and acquisition rate of each instrument should be taken into account when choosing a system for a particular clinical measurement.© (2009) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.