We report fracture toughness data for the reduced activation tempered martensitic steel Eurofer97 in the lower to middle transition region. The fracture toughness was measured from tests carried out on 0.35T and 0.87T pre-cracked compact tension specimens. The data were first analyzed using the ASTM E1921 standard. The toughness-temperature behavior and scatter were shown to deviate from the ASTM E1921 standard predictions near the lower shelf. Using the method of maximum likelihood, the athermal component of the master-curve was calculated to better fit the data from the lower to the middle transition region. We showed that these master-curve adjustments are necessary to make the T-o values obtained near the lower shelf with 0.35T C(T) specimens consistent with those obtained in the middle transition region with 0.87T C(T) specimens. (C) 2008 Elsevier B.V. All rights reserved.