Abstract: A method for automatically closing an open end of a sample vessel with a closure cap, including, inter alia, the steps of grasping an upper part of the closure cap at its outer circumference by means of a cap gripper with at least two gripper fingers comprising respective top thrust ledges extending at least in part over a recess provided by a lateral gripping face, and of pushing the closure cap into the open end of the sample vessel by means of the top thrust ledge. In addition, a respective movable cap gripper for automatically closing the open end of the sample vessel with the closure cap as well as a respective sample vessel closure system is provided.