The invention relates to location determination apparatus for determining a location of a first object (2) like a catheter within a second object (3) being, for example, the heart of a person. The first object comprises a first ultrasound unit, and a second ultrasound unit (5) is located outside the second object. A location determination unit determines the location of the first object within the second object based on ultrasound signals transmitted between the first ultrasound unit and the second ultrasound unit. This allows determining the location of the first object within the second object reliably in a way which is an alternative to using a transmission of electrical signals for determining the location and which may lead to an improved accuracy of determining the location.
