An unexplained incomplete union of the inferior articular processes of the lumbar vertebrae is presented. This has the typical roentgenographic appearance of an ununited epiphysis. Separate epiphyses for the articular processes are not described in the present texts of embryology or anatomy or in the available literature. This condition has been illustrated and described in detail, because it may assume medicolegal significance when misinterpreted as fracture. When one becomes familiar with the typical roentgenographic appearance, the condition offers no diagnostic difficulties. We believe this is an ununited epiphysis, probably anomalous, of the inferior articular process of the lumbar vertebrae. As stated before, embryological confirmation is lacking. It seems logical to assume that the anomaly is not responsible for the symptoms present in the cases described.