Abstract: Apparatus for measuring blood parameters such as chromophore, for example haemoglobin, concentration and blood flow detects light scattered from tissue surface (20) with a multispectral detector (24) that is sensitive to light across a range of different wavelengths. Algorithms are described that demonstrate extraction of chromophore information from scattered light occupying two, red and green or blue, or three bands of the visible spectrum. Simultaneous extraction of blood flow information from scattered laser light occupying either the same or a distinct spectral band is also described.