A hydraulic system (1) is disclosed comprising a pressure source (2), at least a hydraulic consumer (12, 13), and a pressure booster (16) arranged between the pressure source (2) and the hydraulic consumer (12, 13), wherein inactivating means (17) are provided inactivating or activating said pressure booster (16), said pressure booster (16) and said inactivating means (17) being part of a booster module (11). The operational possibilities of such a hydraulic system (1) should be extended. To this end the booster module (11) is part of a valve block (3), said valve block (3) comprising said booster module (11) and at least one valve module (9, 10) controlling said hydraulic consumer (12, 13).