A linear guidance system having a guide rail and a carriage. The carriage is guided displaceably on the guide rail by way of at least two ball bearings, wherein the ball bearings respectively comprise a plurality of balls and a strip-shaped ball cage. The guide rail has running surfaces and the carriage has running surfaces for the rolling movement of the balls of the ball bearings. The ball cage has a plurality of substantially circular through openings which are arranged in succession in a row and into which the balls are inserted, wherein the inside diameter of the through openings tapers conically in the direction from a running surface of the guide rail to the associated running surface of the carriage to an inside diameter or is constricted by limiting means to an inside diameter which is smaller than the diameter of the balls so that the balls are secured in the through openings to prevent them from falling out of the through openings in the direction of the running surface of the carriage.