The 2000 interim version of the AASHTO LRFD Bridge Design Specifications has extended the applicability of the provisions for the design of composite plate girders in positive bending to include 485-MPa High-Performance Steel. The change made in the 2000 interim code is based on analytical work. This paper provides a summary of experimental work conducted with the purpose of verifying the safety of the proposed recommendation. The results of the two tests conducted indicate that, although slightly overconservative, the code's current strength predictive equation with the proposed recommendation is adequate. It was also observed that the tension flange of composite flexural members constructed using HPS-485W steel could achieve large levels of tensile strains without fracture.