The present invention provides a medical tube mainly comprising a thermoplastic resin wherein the surface contacting the blood has been subjected to a heparinizing treatment and wherein quality defect due to whitening and oil defect is reduced. According to the present invention, there is provided a medical tube wherein an antithrombotic material is coated on the inner surface of a tube prepared by a melt extrusion molding of a composition comprising a thermoplastic resin and a plasticizer, characterized in that the difference (”L) between the brightness of the medical tube before coating and the brightness of the medical tube after coating measured in accordance with JIS Z 8722 is 1 or less.
