Abstract: Apparatus for making a yarn comprises two juxtaposed, closely spaced apart twisting drums (1), which are adapted to be driven in the same sense, and an inclined fiber-guiding duct (4), which succeeds fiber-opening means (3) and protrudes into the generally triangular twisting space (2) between the two twisting drums (1) and serves to supply singled fibers in an entraining air stream to the generally triangular twisting space (2).In order to ensure a supply of properly oriented and uniformly distributed fibers into the generally triangular twisting space (2), the length (L) of the shortest boundary wall (5) of the fiber-guiding duct (4), which wall faces the generally triangular twisting space (2), is at least as large as the average length of the longest fibers to be processed in the apparatus, the ratio of the length (1) to the width (b) of the flow area is between 10:1 and 2:1, and the entraining air stream has a mean velocity of flow corresponding to a Reynolds number of 5,000 to 50,000.