The present invention relates to an optical flow cell (1) for a measuring device, having an input light guide with a light exit surface, an output light guide with a light entrance surface, said input light guide and output light guide being integrated with a holder (30) to form optical flow cell (1), and wherein the holder (30) extends along a first axis (A) and has a through hole (31) for receiving a flow of a sample fluid, said through hole (31) being transversal to said first axis (A), and the input light guide and output light guide further are arranged in said holder (30) so that the light exit surface and the light entrance surface extend into said through hole (31) and are arranged to be in optical alignment with each other and at a first distance from each other. The invention also relates to a measuring device having at least one optical flow cell (1).