An comparison of absorbed dose rates,). (D 07 0 t & , in tissue at radiation protection levels for beta dosimetry was performed between two national laboratories, the D. I. Mendeleyev Institute for Metrology (VNIIM) in St. Petersburg (Russia) and the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig (Germany), in 1999 and 2001 using flat ionisation chambers as transfer standards. The dose rates were determined at the calibration distances by measurements with the primary standard measuring devices of VNIIM and PTB with extrapolation chambers to realise the unit of absorbed dose rate to tissue for beta radiation. In the two steps reported on here, transfer chambers of VNIIM and PTB were calibrated in beta radiation reference fields at VNIIM and at PTB. The values of the calibration factors for the flat ionisation chambers agreed within ± 2 % for 90 Sr/ 90 Y, 85 Kr and 204 Tl and ± 4 % for 147 Pm beta radiation.