Abstract: Fancy yarns such as knop or stripe yarns are produced by supplying an effect yarn or roving to a foundation yarn or roving during the operation of spinning but before the foundation yarn reaches the twisting spindle. The effect yarn is kept under a tension which is adjusted to cause the yarn to oscillate with respect to the foundation yarn. Oscillation builds up layers of effect yarn at intermittently spaced locations along the foundation yarn which constitute irregular knops or stripes on the yarn. The twist of the effect yarn in the finished fancy yarn will be found to reverse with each succeeding layer in the knop. The invention enables fancy yarns to be readily produced on ordinary spinning frames without the provision of interrupted feeds or other special features on the frame.