[en] Primary standards of cesium-137 are of great importance for precise radiation measurements because, due to its simple decay-scheme and long half-life, it is widely used for the calibration of radiation detectors. Also ¹³⁷Cs is used for the measurement of fission-yield and uranium burn-up in reactor engineering studies. In view of these, an international intercomparison was organised on a limited scale to correlate the standards established at the Bhabha Atomic Research Centre (BARC), Bombay(India) and Physikalisch-Technische Bundesanstalt (PTB), West Germany. The ''efficiency tracing technique'' was developed at BARC for the primary standardization of ¹³⁷Cs for this intercomparison. Two tracers, namely ⁸²Br and ⁶⁰Co, were employed to trace the beta efficiency of the 4 πβ-γ coincidence counting system. It is shown that this technique offers high accuracy and inherent reliability. The ''tracing-technique'' for ¹³⁷Cs standardization is briefly described. The gravimetric method of dilution and preparation of mixed sources of ¹³⁷Cs - ⁸²Br and ¹³⁷Cs - ⁶⁰Co are given. The various counting parameters and settings are included. Data reduction and the estimation of systematic and statistical errors are discussed. The results of the intercomparison, which are also included, show that the agreement between the measurments of BARC and PTB is within 0.5%. (author)