At least 45 people have been killed in blasts near the Shia shrine of Sayyida Zeinab, south of the Syrian capital Damascus, state media say, the BBC reports.
The Islamic State group said on social media it had carried out the attack.
The shrine, which is highly revered by Shia Muslims, has been targeted before, most recently in February last year.
The attacks came as delegates from the Syrian government and opposition groups gathered in Geneva for tentative UN-sponsored peace talks.
The head of the Syrian government delegation at the Geneva talks, Bashar al-Jaafari, said the attack confirmed the link between the opposition and terrorism.
The main opposition group has backed down from its threat to boycott the talks, but says the Syrian government must meet key demands if negotiations are to start.