The 1990–91 Lancashire Cup was the 78th occasion on which the Lancashire Cup competition had been held. Widnes won the trophy by beating Salford by the score of 24-18 in the final.
Background
The total entrants remained the same as last season, i.e. at 17.
This necessitated the need for a preliminary round (consisting of just 1 game. The first round (proper) then involved 16 clubs.
1 * The first Lancashire Cup match to be played at Rochdale Hornets's new ground
2 * The first Lancashire Cup match to be played on this ground, one of many used by Fulham during the nomadic period between 1985 and 1993
3 * The attendance is given as 11,708 in the official Widnes archives - RUGBYLEAGUEproject gives the attendance as 12,028.