The 2003 NatWest Series was a One Day International cricket tri-series sponsored by the National Westminster Bank that took place in England between 26 June and 12 July 2003. The series involved the national teams of England, South Africa and Zimbabwe. Ten matches were played in total, with each team playing one another thrice during the group stage. The teams which finished in the top two positions following the group stages qualified for the final, which England won by defeating South Africa at Lord's on 12 July by 7 wickets. Preceding the series, England played Zimbabwe in a two Test series, while following the series, South Africa played England in a Test and One Day International series.