A hydraulic system of a transmission includes a plurality of pressure control valves. A pilot force component and an actuating force component of additional pressure control valves are applicable in the direction of a first end position of a valve slide. A downstream pressure of the additional pressure control valves is applicable in the direction of a second end position of the valve slide. Clutch valves are configured to be brought into operative connection by a pilot-controlled valve unit with an area guiding pressure of a primary pressure circuit or with an additional valve unit. The additional valve unit is a pressure-limiting valve with a predefined pressure level adjusted upstream of the additional valve unit and connected downstream to a low-pressure area.