Abstract: A method and apparatus for cleaning of a dialysate circuit located downstream of the dialyzer in a dialysis machine is described. The method comprises injecting a cleaning agent into the dialysis machine at a point between the dialyzer inlet port and the downstream dialysate circuit in an amount sufficient to substantially reduce the deposit in said downstream dialysate circuit; permitting flow of the agent towards the downstream dialysate circuit; and substantially preventing flow of the agent toward the dialyzer inlet port. The injection adaptor apparatus comprises an injection connector downstream of a backflow prevention valve, and two flanking tubing connectors. The apparatus is inserted at a point downstream of the dialyzer inlet port, and cleaning agent is injected into the injection connector. An adaptor to facilitate handling of cleaning agent during manual agent injection is also described. Additionally, an automated agent injection apparatus is described.