Background. Syringomyelia and Chiari Syndrome are classified as rare diseases, but current known occurrence in Europe is missing. The increased ability to diagnose these pathologies by magnetic resonance imaging and its widespread availability has led to an increase of reported cases, often asymptomatic, with the need to standardize definitions, diagnostic criteria and treatments. Aims. We present shared Interregional Recommendations developed with the primary aim to estimate Syringomyelia and Chiari Syndrome prevalence and incidence in North Western Italy, with special reference to symptomatic forms. Methods. An agreement for the standardization of definitions, classifications, diagnostic criteria and surgical Recommendations was reached by the multidisciplinary Interregional Piemonte and Valle d’Aosta Chiari-Syringomyelia Consortium (Delphi method); next, in 2011 a census for Syringomyelia and Chiari Malformation was performed through the Interregional Piemonte and Valle d’Aosta Rare Disease Registry, integrated by a dedicated form in order to estimate prevalence and incidence. Results. 436 patients, 292 females, met shared interregional diagnostic criteria. Syringomyelia prevalence was estimated in 4.84:100 000; Chiari Malformation prevalence was 7.74:100 000; incidence was 0.82:100 000 and 3.08:100 000 respectively. Demographics, neuroradiological parameters and aetiology were reported (in symptomatic and asymptomatic forms). Finally, symptoms and signs, familiar and natural history were analyzed. Conclusions. First Italian epidemiological data (prevalence, incidence) on Chiari and syringomyelia was collected, according to shared diagnostic Recommendations. Future perspectives include the adoption of these Recommendations at national level to standardize the access to diagnosis and care process and promote multicenter clinical trials.