In a silicon-controlled rectifier, an anode region includes p-type anode well regions which are laterally surrounded by an n-type well region. A length of a p-type anode well region, as measured in a first direction, is greater than a width of the p-type anode well region, as measured in a second direction perpendicular to the first direction. A p-type well region meets the n-type well region at a junction, wherein the junction extends between the p-type well region and n-type well region in the second direction. A cathode region includes a plurality of n-type cathode well regions which are formed in the p-type well region. A length of an n-type cathode well region, as measured in the first direction, is greater than a width of the n-type cathode well region, as measured in the second direction.