Anesthetic equipment, including breathing circuits, has evolved over time. The T-piece circuit, in its various forms, was designed to meet the needs of its time. As equipment and techniques have moved on, it is timely to consider the place of the T-piece in modern pediatric anesthetic practice. Today the circle system is a ubiquitous part of anesthesia. When integrated with a modern anesthetic machine it offers precise control of ventilation together with continuous monitoring of airway pressure and flow: but at the cost of complexity. In comparison the T-piece offers a simple cheap lightweight design, so ergonomic in use that it almost becomes part of the anesthetist: but lacks the control and the barriers to unsafe use of more sophisticated systems. In addition, it requires high fresh gas flow adding to cost and environmental pollution. This pro-con debate discusses whether there remains a case for continuing to use the T-piece circuit in preference over other options. Possible indications for the T-Piece are discussed together with alternative strategies. The limitations of the circle system, the T-piece, and other alternative (such as self-inflating resuscitator bag) are discussed with respect to pediatric anesthetic practice. JK: When I finished medical school in 1997 and started my residency in anesthesiology, at the University Hospital of Cologne, I had my first and last contact with T-piece in anesthesia. Most of the operating theaters, including the ENT theater, were located in separate buildings. At that time, it was the usual procedure to transfer children still endotracheally intubated from theater to the postanesthetic care unit (PACU) and for extubation to be performed by PACU nursing staff. A "Kuhn-System," comparable to Jackson Rees System, was used during transfer and in PACU until extubation.