Search for alloys with improved high temperature specific strength and creep resistance properties for aerospace applications has led in the last decades to sustained research activities to develop new alloys and/or improve existing ones. The maraging steels evoked tremendous interest, especially in the aerospace world. Extra low carbon, high nickel, iron based alloys held great promise of providing an extraordinary combination of structural strength and fracture toughness. Applications of this alloy include aircraft structural components and rocket engine case for Satellite Launcher Vehicles. The objective of this work is to study the creep behavior of a solution treated Maraging 300 alloy. Constant load creep tests were conducted with this alloy at 550°C and in a stress range of 200 to 500 MPa. The creep parameters are determined. Samples with a gage length of 18.5 mm and a diameter of 3.0 mm were used for all tests.