1965–66 was the fifty-third occasion on which the Lancashire Cup completion had been held. Warrington won the trophy by beating Rochdale Hornets by the score of 16-5 The match was played at Knowsley Road, Eccleston, St Helens, Merseyside, (historically in the county of Lancashire). The attendance was 21,360 and receipts were £3,800 It would be almost another 20 years before the attendance would again exceed 20,000