Abstract: Disclosed is an apparatus for treating tail yarns in textile spindle assemblies of textile spinning machines, twisters or the like, wherein a stationary upper slit ring and an axially slidable lower slit ring are mounted on a base portion of a spindle to form a tail yarn gripping means. The pressed state of the tail yarn gripping means is released by sliding the lower slit ring downward by rotational centrifugal force. The tail yarn can be securely fixed to the tail yarn gripping means and the yarn underwindings can be automatically removed from the tail yarn gripping means during the operation of the machine.When a flange of the upper slit ring is perforated with a plurality of yarn passing openings, the tail yarn released from the means for holding the yarn underwindings is retained by this yarn passing opening, which prevents adverse effects to the traveler in the early stage of winding, resulting in prevention of the occurrence of yarn breakage or the deterioration of yarn properties.