Riot police have fired tear gas and water cannon at opposition supporters marching in the Togolese capital, Lome.
Togo's main opposition party, the Union of Forces for Change, want the 24 April presidential elections postponed, saying they are being held too soon.
Supporters of the ruling party also held a rival rally in Lome.
The BBC's Ebow Godwin says opposition supporters fought running battles with riot police as they tried to keep the two rival groups apart.
The vote was called after President Gnassingbe Eyadema died in February.
His son, Faure Gnassingbe, was originally installed in office by the Togolese Army, but he later bowed to international pressure and stepped down, agreeing to contest an election.
The opposition say they have not been given enough time to mount a proper campaign.
Emmanuel Bob-Akitani, Vice-President of the Union Forces for Change party, will stand as the main opposition candidate against Faure Gnassingbe.
But ruling party supporters say any delay in the poll would be a danger for the country.
© BBC MMV