This report deals with a comparison of national standards of rf voltage organized by the radiofrequency working group of the "Comite Consultatif d'Electricite" of the Bureau International des Poids et Mesures (BIPM). It was done by sending round transfer standards, for each of which the participating laboratories had to measure the rf-dc difference for a reading of 1 V at frequencies from 100 MHz to 1 GHz. The seven standardizing laboratories participating in this comparison were: ASMW (GDR), EQD (UK), NBS (USA), NML (Australia), OMH (Hungary), PTB (FRG) and VNIIM (USSR). The Physikalisch-Technische Bundesanstalt (PTB) acted as pilot laboratory. Two kinds of transfer standards were circulated in two separate cycles: two resistance mounts (50 Ω and 75 Ω input impedance) and two thermal converters made available by the PTB and the OMH. The results are presented in two tables and 16 bar charts. A weighted mean value for each transfer standard and frequency was calculated from the measurement results. Good agreement between the measurement values of all participants was achieved. For resistance-mount transfer standards the deviations of the measured values from the weighted mean values were ≤ 4 × 10-3 for all frequencies up to 1 GHz, for thermal converters all deviations were ≤ 3 × 10-3 at 100 MHz and ≤ 1.2 × 10-2 at 1 GHz (excluding one measurement point). All the transfer standards remained sufficiently stable over a measuring period of more than 5 years.