Method for sterilising containers (10), wherein a treatment head (5) is guided into the interior of a container (10) to be sterilised and the treatment head (5) emits radiation in the interior of the container (10) at least intermittently over a predefined time period (dT), wherein the container (5) is moved relative to the treatment head (5) in a longitudinal direction (L) of the container (10) at least intermittently at a relative movement speed (v) over the predefined time period (dT). According to the invention, this relative movement speed (v) of the treatment head (5) located in the interior of the container (10) varies over the predefined time period and is controlled as a function of an internal profile (10a) of the container (10).