Supporters of the Catholic Women's Network accused leading Roman Catholic clergy in Wales of being sexist.
The demonstration was mounted at St David's Cathedral, Cardiff, shortly before Archbishop Aloysius Ward washed the feet of 12 men in the congregation in the tradition of the Last Supper when Jesus washed the feet of his disciples.
Surprised worshippers arrived for the service to find a large banner outside the cathedral proclaiming "Wash Women's Feet Too".
As the Archbishop continued with his service inside, 30 women held their own ritual outside on the pavement, producing a wooden chair, a bowl and jug of water. Earlier they handed out leaflets and tried to argue their case with clergy arriving for the service. Several priests avoided the protest by using a side entrance.
Sheila McBride, of South Shields, who travelled to Wales for the pavement service, said most Catholic diocese were more enlightened and chose to include women members in the ceremony. "I think it is terrible to exclude women like this and it completely changes the meaning. Washing of feet is supposed to be a symbol of service to others, love and unity."
Ann Farr, spokeswoman for the Network, was among those who had her feet washed outside the cathedral. "To exclude women turns the whole Maundy Thursday tradition into a symbol of exclusion and division," she said.
Father John Lloyd denied the service ignored the role of women. "The diocese is simply following Vatican instructions."