Many researchers reporting the transient rheology of fiber suspensions have not experimentally verified the initial fiber orientation. An assumption for the initial orientation is then required to simulate the fiber orientation evolution and stress response. Measurements of fiber orientation obtained prior to testing in a rheometer can confirm the homogeneity of fiber orientation throughout a sample and repeatability between multiple samples. In this work, the transient rheology of glass fiber suspensions above 0.5 mm in length was measured in a sliding plate rheometer with the initial fiber orientation generated through compression molding, flow reversal, and injection molding. Measurements of shear stress and fiber orientation were obtained to evaluate each sample preparation method and to gain insight into the stress -microstructure relationship. Preshearing and applying flow reversal was used in an effort to control the initial fiber orientation for transient shear stress measurements, but fiber orientation did not change significantly, and the stress response was variable with little stress overshoot. Samples created through injection molding provided a repeatable transient stress response with measurable changes in fiber orientation. Components of the fourth order orientation tensor were also reported to compare with current theories for stress. An overshoot profile in fiber orientation was not observed during the startup of flow, and little change in orientation occurred during the flow reversal tests. Based on experimental values of fiber orientation, a stress theory dependent on the fourth order orientation tensor was not able to reflect an overshoot in shear stress and could, at best, capture the steady state. (C) 2016 The Society of Rheology.