The authors analyze the incidence of early mechanical and infective CSF shunt complications and various factors that might be correlated with the incidence in a series of 170 children affected by hydrocephalus and meningomyelocele (MM), with the aim of finding specific risk factors related to this particular type of hydrocephalus. Factors investigated for correlation with CSF shunt malfunction are the following: level of the spinal malformation, age of the patient at MM repair, age at diagnosis of hydrocephalus, degree of the ventricular dilatation, age at CSF shunt implantation, modality of the surgical procedure, characteristics of CSF at operation. In the first postoperative year following CSF shunting, 45.9% of the patients presented one shunt malfunction, three-quarters of which were due to mechanical causes, and one quarter to infection. Age of the patient at diagnosis of hydrocephalus and at CSF shunt operation did not significantly influence shunt patency, nor did the surgical modality (programmed vs emergency procedure). On the other hand, MM level did influence the outcome of CSF shunting: a higher percentage of malfunctions (and in particular of infective complications) was observed among the patients with “high level” MMs than in the group with more caudal location of the spinal defect. Similarly, the degree of ventricular dilatation correlated with the incidence of complications (more severe ventricular dilatation was associated with the highest incidence of complications). The order in which MM repair and CSF shunting were carried out and the age of the patients at MM repair did not affect the occurrence of mechanical complications, whereas they had a significant effect on the incidence of infective complications. In fact, the rate of overall complications, and of infective complications in particular, was proportional the age at MM repair. Furthermore, the group of children who underwent to MM repair and CSF shunting simultaneously scored the lowest percentage of complications, although these were mainly infections; the highest incidence of complications (and in particular of infective ones) was observed in the children who underwent CSF shunting first. The most striking correlation, however, was found with the characteristics of CSF. While normal CSF values correlated with an overall incidence of complications of 39.2%, abnormal CSF values were correlated with a rate of complications of 90.9%; in particular, the rates of infective complications were 2.7% and 77.3%, respectively. On the grounds of these observations a protocol is proposed of temporary CSF external drainage in children requiring prompt relief of increased intracranial pressure but at risk for the presence of a leaking spinal defect or of a MM left unrepaired for more than 48 h.