The infrared spectrum of polyvinyl nitrate has been obtained in the extended region of 70 to 3600 cm−1. Polarized infrared measurements were made on oriented specimens in the range of 350 to 3600 cm−1. Since x‐ray diffraction patterns indicate no crystallinity, the analysis has been based on an assumed atactic configuration. With the help of previous studies of high‐polymer spectra and results obtained on small molecules, it has been possible to make a complete assignment of all of the expected fundamentals. Dichroic measurements have not only permitted a decision on the assignment of the controversial NO2rocking and bending modes, but suggest certain details concerning the local configuration of the nitrate group. There seems to be evidence that, although the specimen is not crystalline, a significant proportion of the chains have configurations not far from a planar zigzag chain.