Abstract: A longitudinal balance test circuit connects to the tip and ring lines of a pair of telephone wires. It also connects to a shield conductor that extends with the tip and ring lines. The test circuit includes a transformer which has two windings. One winding connects to the tip and ring lines, and it also connects to the shield conductor. The other winding connects to a signal generator that provides an alternating current test voltage with which to test longitudinal balance of the tip and ring lines. A method of testing a telephone line for longitudinal balance comprises: measuring an alternating current test signal applied to a telephone line under test; measuring stressed noise of the telephone line in response to the applied. alternating current test signal; calculating, in response to the measured alternating current test signal and the measured stressed noise, an adjusted value related to longitudinal balance regardless of the length of the telephone line under test; and displaying the adjusted value.