Osteogenesis Imperfecta is a genetic disorder of increased bone fragility and low bone mass. Most cases are caused by a mutation in one of the two genes coding for the type I collagen protein. The correct clinical diagnosis of OI can be difficult sometimes, because of the wide phenotypic range. Therefore collagen I genes mutation identification can be helpful. We screened 23 patients by direct sequencing of the exons encoding the collagen protein. We identified 18 different mutations, while 5 cases were negative because of an uncertain clinical diagnosis or an atypical form of OI not related to collagen I genes. The current medical and pharmaceutical treatments are only symptomatic and do not alter the course of collagen mutations. Cells and gene therapies as potential treatments for OI have therefore to be actively investigated.