Ostitis deformans Paget was relatively recently classified into inflammatory bone diseases, caused by viruses of the group “slow-virus diseases”. Due to repeated claims in older and more recent monographies it is still considered as a disease, which begins at an older age. In fact, it usually becomes manifest at the older age, although it may last from the young age. The original asymptomatic course, however, may escape attention and establishment of diagnosis in younger individuals is often by chance. The course of the process includes three stages, where the initial osteoporosis is easily overlooked and the attention in practice as well as in publications is paid to the later developed medium stage (osteoporosis-sclerotic) and the final sclerotic one. The diversity of symptoms is supported by the observations that these stages may be present simultaneously even in one bone and other parts of the skeleton may be affected by initial manifestations at the time, when the disease occurs at the terminal stage of development elsewhere. The paper documents the examples of development of these changes and points out the need of dispensary of these patients at special centers for tumors and tumor-like bone diseases.

        Key words: ostitis deformans Paget – bone diseases