A study of the tensile behavior of ultra-high-molecular-weight polyethylene over a range of strain rates showed that its strain rate sensitivity was a function of the strain. This was related to a flow rule developed for this material in a previous study on compressive behavior. This flow rule is an adaptation of that of Hill, in which the anisotropy coefficients are power-law functions of the extension ratios. It is used in conjunction with an Eyring process. The observed rate dependence of the tensile behavior conformed with that obtained with the power-law flow rule and could be used to derive a value of the power-law coefficient. Independent observations were made of the relationship between the axial and transverse strains in tensile specimens with inhomogeneous strain fields. A constitutive model was developed that incorporates the new flow rule and was implemented in a finite element analysis. When this analysis was used to model the inhomogeneous tensile specimens, it gave predictions of the axial and transverse strain that were consistent with the experiment when the power-law coefficient was the same value as that derived from the study of the rate dependence. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121:2936-2944, 2011