Grazing of ponderosa pine needles by pregnant cows may cause abortion. The abortions are frequently accompanied by retained placenta. Death is not uncommon in cows that abort. Ten cows were placed on a ponderosa pine needle experiment. Six of these cows were fed pine needles and four served as controls. All six cows receiving pine needles aborted, and three of them died shortly after the abortion. Death was due to a severe septicemia. Although the cows were necropsied shortly after death, all tissues were necrotic. Other lesions are described. Three of the six calves died shortly after the abortion. The other three were small and weak but survived due to intensive care.