Gated pipelines have traditionally been designed using an approximate method developed prior to the introduction of digital computers. Hence, the design of systems to give nearly uniform discharge from each orifice has not been possible. In this paper the results of tests on a particular gated pipe are summarized. The exact theory for spatially varied flow in a multi-orificed pipeline is described and applied to the gated pipe and the predicted performance correlated with the experimental results. The effects on the uniformity of outflows caused by varying pipeline slope, pipe diameter, number of gates, gate area and mean outflow are illustrated. It is shown that, for all the typical gated pipe situations analysed, maximum outflow uniformity is obtained with the pipeline sloping uphill in the direction of flow. This is contrary to the normal recommendation for sprinkler and trickle irrigation systems. The diagrams presented should serve as guidelines for the design or management of systems using this type of gated pipe.