On 28 September 2003, Italy experienced the worst blackout in its history. Other blackouts also occurred in August and September 2003 in the USA, Denmark, Sweden and, on a smaller scale, in England. The coincidence of these events could make one think that liberalization endangers the security of electricity supply. This article attempts to shed some light on this hypothesis starting from the root causes of the 2003 blackouts. The conclusion is that the regulatory and organizational changes in the electricity sector led an increase in the electricity exchanges and modified the incentives of the transmission system operators (TSOs). In a liberalized context, blackouts should be prevented by a good mix of regulation, industrial initiatives and public intervention. This is the only way to maintain the needed collaboration between the TSOs and to ensure the development and maintenance of the transmission equipment.