A urinary catheter assembly comprising a urinary catheter (1) having on at least a part of its surface a hydrophilic surface layer (6) intended to produce a low-friction surface character of the catheter by treatment with a liquid swelling medium prior to use of the catheter and a catheter package (7) having a cavity (11) for accommodation of the catheter (1). The package (7) includes a compartment (12) having walls of a gas impermeable material and accommodating said liquid swelling medium or a catheter pretreated therewith for long time preservation of said low-friction surface character and provision of a ready-to-use catheter assembly. <;IMAGE>;