In this study, I review, clinically and radiographically, 303 patients with 460 single or multirooted endodontically treated teeth. In all teeth, the therapy was performed by me with the use of final restoration of the crown with or without post and full cast crown coverage after treatment. The teeth were functioning for at least 3 years, without having received any other type of dental work since then. I evaluated the existence of vertical root fracture, the function of the teeth, the type of root canal therapy, the type and length of the post, and the type of retention of the post used in all 460 teeth. After statistical evaluation of the results, I found that 3.69% of the teeth had had vertical root fracture. Computer analysis, simple correlation hypothesis, and distribution method with 1 degree of freedom revealed significant correlation between vertical root fracture and the technique of instrumentation and obturation of the canal (p = 0.025), the length of the post (p = 0.05), and the existence of the post (p = 0.05). On the contrary, I found no correlation between root fracture and type of retention of the prefabricated post used with respect to the method of obturation. © 1990.