The invention relates to a measuring cell for measuring optical properties of liquids, comprising a measuring chamber (16) which on one side is delimited by a transparent window (11) and a reflector (30), positioned on the opposite side of the measuring chamber (16), which reflects the light incident on it through the measuring chamber (16) and window (11) to the outside. According to the invention the measuring cell for liquids is especially easy to clean and allows for easily reproducible measurements for a long period if an additional transparent window (33) is arranged between the reflector (30) and the measuring chamber (16) which window delimits the measuring chamber (16) towards the other side.