The anisotropy of evaporated Permalloy films (composition near zero magnetostriction) deposited on glassat 45° to the substrate normal and at a substrate temperature of 200°C has been studied after anneal forseveral hours at 300°C. After anneal the room temperature easy axis of films with positive magnetostrictionis in the original direction. However, films with negative magnetostriction develop a new room temperatureeasy axis 90° to the original one; at 300°C the easy axis is in the original direction. Application of a largemagnetic field in any direction during anneal does not influence the final magnetic anisotropy in either case.These effects are qualitatively explained by assuming the anneal to increase the tension along the long axisof oblique-incidence chains, a process which converts surface energy into strain energy. Anisotropy wasmeasured by resonance in a coaxial bridge over the frequency range 50 Mc to 2100 Mc. A rectangular coaxialcavity is used which can be heated to 500°C in a vacuum of10−6 mmHg; continuous angular orientation ofthe film is possible with a resolution of ±0.5°. Bridge balance is good enough to permit samples of less than100 A thickness to be measured.