The invention relates to a method and apparatus for determining a respiration of a subject (305) in which, with a single multi-axial accelerometer (310) positioned on a body of the subject (305), accelerometer signals are generated (101) indicative of the acceleration of the subject (305) along different spatial axes, a vector magnitude signal of the acceleration of the subject (305) along the different spatial axes is calculated (102) from the accelerometer signals, a non-respiratory motion contribution to the acceleration along the different spatial axes is identified (103, 203) from the vector magnitude signal, which non-respiratory motion contribution is not caused by the respiration, and a respiration signal indicative of the respiration of the subject is determined (104, 204) by filtering the non-respiratory motion contribution from at least one of the accelerometer signals. In this way a method is provided which determines the respiration of a subject (305) with a single accelerometer (310) in an efficient and, for a patient, comfortable way.