A comparison is made of traffic conditions in the Warsaw Railway Junction before and after its electrification between 1933 and 1938 by a group of British firms.The paper gives a survey of the equipments used and describes the reasons which led to the selection of a voltage of 3 000 volts d.c. for this scheme. A summary of the improvements achieved by the electrification of the suburban service is given and maintenance troubles experienced in the early stages of the electrification are described.