To optimize the performance of oil-free reciprocating piston compressors, the leakage flow through the piston seal has to be minimized. Therefore, the effects of the geometrical parameters and shapes of labyrinth seals on the leakage flow are examined. The main geometrical parameters and shapes are investigated by means of computational flow dynamics simulations. The optimum geometries obtained from the simulations are experimentally tested on a compressor rig. The rectangle labyrinth shows the lowest leakage followed by a novel semicircle geometry and the triangle geometry shows the highest leakage flow among the labyrinths. The straight seal exhibits the highest leakage flow rate. It can be concluded that the rectangle labyrinth reduces the leakage flow rate in the most efficient way.