The 1891 Championship was won by Scotland, the fourth time the country had topped the table, but the first time Scotland had taken the Triple Crown title.
Rule changes this year, included the introduction of penalty goals, as although penalty kicks were introduced in 1882 no goal attempts could be made from one until this season. The two umpires were renamed as touch-judges and their powers were reduced to mark the spot where the ball left the field of play; a status that remained until additional powers were reinstated in 1982.
The matches for this season were decided on points scored. A try was worth one point, while converting a kicked goal from the try gave an additional two points. A dropped goal was worth three points. Penalty goals were now worth three points, as although introduced in 1882, no attempt could be made from a penalty kick at goal until this season.