Measurements of power loss have been made on individual grains in polycrystalline specimens of commercial 3% grain-oriented silicon-iron under longitudinal and transverse ac magnetization and rotational flux conditions. The domain configurations have also been observed using a stroboscopic Kerr magnetic-optic apparatus. The effect of longitudinal stress and dc bias fields on the domain patterns and power loss under these ac magnetization conditions has also been investigated. It can be concluded that the highest power loss occurs under pure rotational flux conditions and that the application of longitudinal compressive stress increases the power loss, but to a lesser extent when a transverse ac flux is present. The application of a longitudinal dc field increases the power loss for all ac magnetizing conditions, and it has been observed that a longitudinal tensile stress has the opposite effect on the domain configuration to the application of a transverse dc field.