Neville Hayes was one of the best Australian butterfly swimmers of the 1960s. Prior to the 1960 Roma Olympics Hayes set world records in the 110 yard and 220 yard butterfly. At the Roma Games he won silver in the 200 metres butterfly and silver in the 4 × 100 metres medley relay. At the 1962 British Empire and Commonwealth Games in Perth Hayes won silver in the 110 yard and 220 yard butterfly.
Hayes then spent some time in the United States where he attended Harvard University. From 1964 to 1967 he swam for the Harvard Crimson team, setting several records and receiving All-American honours in the 200 yard butterfly.