You will be given the chance to select your t-shirt size in the run-up to the event. If it does not fit when you receive it after crossing the Finish Line and you would like to exchange it, please send your t-shirt, along with a note including your full name, bib number, preferred t-shirt size and full postal address, to: Freepost - LONDON MARATHON EVENTS. We will then send you the requested t-shirt within two weeks.