A plasma treatment unit having a high-voltage stage (5, 6), arranged in a housing, for generating high-voltage signals suitable for the generation of a plasma, and having a head part (2) which is connectable to the high-voltage stage (5, 6) and in which there is situated an electrode arrangement (13) shielded by a dielectric (9), is suitable for plasma treatments in particular in the body interior by virtue of the fact that the head part (2) has an elongate transition piece (10) which is attachable to the housing and on that end of which which is not connectable to the housing there is arranged a treatment head (16, 16′), the dimensions of which perpendicular to the longitudinal direction of the transition piece (10) greatly exceed the dimensions of the transition piece (10), and that, in the treatment head (16, 16′), the electrode arrangement (13) forms a spatially closed flexible sheath (12) around a resiliently elastic core (14) and is covered at its outer lateral surface by a thin layer (15) of the flexible dielectric (9), such that the treatment head (16, 16′) can, as it is inserted into a body interior, assume the shape of the surrounding tissue in the body interior.