The invention relates to a rudder for ships, having a rudder blade, which is intended to be arranged on a hull such that said rudder blade can rotate about a rotation axis, and a rudder stock for exerting a torque on the rudder blade. A rudder-monitoring device (3) is provided, having at least one sensor (33) arranged on the rudder blade (22) or rudder stock (21) for picking up a measurement signal on the rudder blade (22) or rudder stock (21) and at least one computation unit (31), which is arranged on the rudder blade (22) and is connected to the at least one sensor (33), for evaluating and/or transmitting a measurement signal picked up by the at least one sensor (33). In this manner, a rudder for ships is provided, with which the availability and mechanical integrity of a rudder can be monitored during operation of a ship in a simple manner and in any desired situation, for example including in open sea.