This study deals with 49 fractures of the dens treated at the Orthopedic Department of Athens University during the past 17 years. These fractures represent 14.2% of all cervical fractures treated during the same period at our department. Forty-one cases have been reviewed and analyzed, the average follow-up time being 10 years (1-16). Pseudarthrosis was found to be present in seven cases (17%), and its relationship to different factors was examined. The type of fracture and particularly the direction of the fracture line were found to be major factors leading to pseudarthrosis. Many other factors, such as displacement, traction, the stability obtained, the presence of associated injuries, and the time elapsed till treatment was started, as well as the age of the patients, seem to play--alone or in combination--important roles in the development of pseudarthrosis. These factors have been classified according to their importance and graded. With a total of 10 points or more a dens fracture is characterized as a fracture "at risk of pseudarthrosis", i.e., a fracture with a higher possibility of developing a pseudarthrosis. This knowledge may contribute to proper and earlier management of such an injury.