In a method and apparatus for automatic positioning of a patient relative to a medical device, the patient is positioned on a patient support of the medical device in a detection area of an optical position determining device of the medical device. The optical position determining device has at least one three-dimensional light curtain arrangement. A start position of the patient is detected by the optical position determining device and a position deviation between the start position detected and a target position stored in a control processor is determined. Depending on the position deviation, the patient support is automatically positioned in three dimensions.