The paper reports the case of a 6-year-old child bitten by a snake initially mistaken for a viper who needed to be transported to the hospital with a medical ambulance for fear of envenomation by viper. From the WHO epidemiological data more than 5 million snake bites occur worldwide each year, resulting in 2.5 million poisonings and 81,000 to 138,000 deaths. In Italy are four species of viper otherwise distributed throughout the territory. In ED it is important to ascertain what kind of snake it is (by consulting experts such as forest rangers or doctors of Anti-Venom Centre) and to remember the criteria that indicate the Fab antivenom. The rapid administration of the Fab antivenom if indicated prevents major complications and reduces the risk of compartment syndrome with the need for fasciotomy.