This paper describes some of the most used methods for caries lesion progression measurement in in vivo and in vitro research. Clinical measurements are usually limited to visual inspection. Currentl available scoring systems and statistical analyses, making use of changes in lesion stage, have the potential to make caries clinical trials more efficient. A method for light fluorescence measurement is capable of measuring small changes in mineral loss for early lesions. In the laboratory, mainly destructive methods are used. The most widely accepted gold standard at the moment is transversal microradiography (TMR). Other microradiographical methods are described, that allow for longitudinal measurements.