The paper presents the results obtained in the assurance of traceability along the whole chain: production, distribution, use in hospitals, for the activity measurement of radiopharmaceuticals containing 186Re, 188Re and 186Re + 188Re mixtures. Standardization of the solutions, 4piPC-beta-efficiency relations and responses of a Centronic IG 12/20A ionization chamber and other radioisotope calibrators are presented. Gamma-ray and bremsstrahlung radiation contributions in the total response were evaluated. Some of the relevant results were compared with literature data.