The Laboratory of External Dosimetry Studies and Researches (LRDE), associated laboratory to the Bureau National de Métrologie, is strongly involved in the reference establishment and calibration of instruments in neutron radiation fields provided by 241Am-Be, 252Cf and (252Cf + D2O)/Cd sources. In 1997, on the request of COFRAC, the LRDE has managed an Inter-Laboratory Test Program in 'neutron dosimetry' to compare the different standard calibration methods. The transfer instrument used was a "Harwell Monitor N91". The results of the participant were in good agreement but the associated uncertainties need to be revised by some of laboratories. According to the Mutual Recognition Arrangement signed in 1999, laboratories for metrology will have to assure the traceability of their references. In 2003-2005, the LRDE organises, with National Physical Laboratory (UK) and Physikalisch-Techische Bundesanstalt (Germany), an international comparison in 'neutron dosimetry'. Two transfer instruments, a "2202D" rate metre and a "Harwell Monitor N91", will be sent in turn to the participant laboratories for measurements at their own neutron sources facilities.