Because of the inadequacy of the fire load concept and of the large subject area covered by ASTM Methods E 119, the results of standard fire tests do not represent either the times for which building elements actually withstand building fires, or “rating” values expressing the “fire endurance quality” of the various building elements on a unique scale. Several areas of the standard are discussed where fire research indicates the need for urgent revisions. To achieve higher economy in design for fire endurance it will become necessary to replace the temperature-time curve by realistic heat flux-time relations characteristic of the specific conditions. For some decades to come progress in fire endurance research will be measured by progress in understanding the behavior of building materials at elevated temperatures.