Ehlers-Danlos syndrome comprises a very heterogeneous group of collagen diseases characterised in clinical terms by fragility and cutaneous hyperextensability, ligamentous hyperlaxity, ecchymosis, scarring, visceral and neurological manifestations. Having been described in detail by Ehlers in 1899 and Danlos in 1908, it was subsequently classified into various clinical types. At present at least 11 forms are recognised on the basis of their clinical characteristics, methods of transmission and biochemical defect; the first four types of the syndrome account for approximately 95% of cases. Almost all forms are transmitted with a dominant autosomic character. Specific genetic mutations have been ascertained whereas the biochemical defect has been identified in numerous types. Ehlers-Danlos type 1 syndrome is the most frequent and most severe form. The biochemical anomaly underlying the altered deposition of collagen fibre is still unknown and this is responsible for the "storiform" appearance of collagen fibre on ultrastructural examination. The authors have described a typical case of "Ehlers-Danlos type 1 syndrome" in which the diagnosis was confirmed by comparing clinical data and the results of ultrastructural tests which revealed the characteristic "pattern" of collagen fibres.