The Siam Cup is an annual rugby union competition held between the Channel Islands clubs of Jersey Reds and Guernsey.

[2] The trophy is a large circular rose-bowl made from coinage of Siam ticals and required the permission of King Rama VI to melt the coins down.

The Cup was brought to the Channel Islands by Lieut-Colonel C H Forty, an officer based in Siam with the Durham Light Infantry.

Following Jersey's rise through the English leagues to Level 2 and turning professional it was argued that it made the competition unfair.

In 2016, it was declared that Jersey could only select players for the Siam Cup if they had been on the island for three years, Guernsey, playing in a league at Level 5, would be unaffected by the change.