In an apparatus and method for examining tissue by transillumination of the tissue, light having different, defined wavelengths is emitted from a plurality of monochromatic light sources into tissue under examination, the light emerging from the tissue is detected by a detector arrangement for detecting the parts of the emitted light transmitted by the tissue, and signals from the detector arrangement are supplied to an evaluation unit. The evaluation unit calculates data with respect to the concentration of the different tissue components in the tissue under examination from the different signals on the basis of stored data that correspond to the light absorption of different tissue components.