[en] 2¹/₄ Cr-1 Mo steel is used worldwide as an elevated-temperature structural material, particularly in steam generation systems. Since this material is often used at service temperatures up to 600⁰C, successful design requires a consideration of its creep properties. Unfortunately, the development of an analytical description of the creep behavior of 2¹/₄ Cr-1 Mo steel is complicated by two phenomena. First, the creep strength of this material is quite sensitive to heat treatment. Second, this material tends to exhibit nonclassical creep under some conditions. In addition, especially in nuclear applications, the material used may be air-melted, vacuum-arc remelted (VAR), or electroslag remelted (ESR). Available creep data from air-melted, VAR, and ESR material have been analyzed. Heat treatments included both annealed and isothermally annealed, with and without a subsequent ''postweld'' heat treatment. It has been found that the elevated-temperature ultimate tensile strength (UTS) is a useful indicator of creep strength for a given heat of material regardless of melting practice or heat treatment. Meanwhile, the nonclassical creep behavior has been attributed to a change in creep mechanism which has been mathematically modeled