The AFL is the latest Australian sporting organisation to support marriage equality, making an eye-catching statement on the outside of its Docklands headquarters.

On Wednesday morning the logo at AFL House was replaced with a prominent 'YES' sign, sending an unmistakeable message that the league is continuing its tradition of taking a leadership role on social issues.

The AFL also considered but decided against replacing the AFL logos on the MCG and Adelaide Oval with the word 'YES' for this weekend's preliminary finals.

However, 'YES' will be painted on Sherrin footballs that will be sent to all 18 clubs and state leagues around the country on Wednesday afternoon.