Abstract: A 3-way stopcock for medical use is described and includes a body or nucleus (1) wherein a principal arm (2) and two secondary arms (3, 3?) converge and a plug or stopper (4) acting inside the body or nucleus (1). According to the invention, the two secondary arms (3, 3?) present initial curved flexible segments (3a, 3?a) having a high elastic index, which respectively extend into parallel final distal segments (3b, 3?b).