A method of modifying a surface of a medical device for implantation or disposition inside a patient is described. The medical device comprises a structure having at least one surface. The method includes the steps of: placing the medical device into a plasma chamber substantially free from contaminants and substantially sealing the plasma chamber from the atmosphere; removing at least an outermost layer of any oxide layer from the at least one surface of the structure by a plasma oxide-removal process, whilst maintaining the plasma chamber under seal from the atmosphere; and subsequently forming a new oxide layer at the least one surface of the structure by introducing at least one gas into the plasma chamber, whilst maintaining the plasma chamber under seal from the atmosphere. A medical device including a bulk material and an oxide layer disposed over at least one surface of the medical device. The oxide layer is substantially pure and free from contaminants.