At least three arrests were made after the demonstration, which was the first such street protest against this week's army takeover
A group of protesters waved banners and chanted anti-coup slogans in Myanmar's second city of Mandalay on Thursday in the first such street protest against this week's army takeover, images on social media showed.
Video on Facebook showed around 20 people outside Mandalay Medical University. One banner read "People protest against military coup."
"Our arrested leaders, release now, release now," the protesters chanted.
At least three arrests were made after the protest.
The demonstration was the first such street protest against this week's army takeover that ousted Aung San Suu Kyi's elected administration. The arrests were confirmed by student activists from three groups, based in Mandalay and Yangon.
Myanmar's army seized power on Monday, overthrowing popular elected leader Aung San Suu Kyi, who is detained and now faces possible charges for import infringements over the alleged possession of six unauthorised walkie-talkies.
Previous Myanmar juntas had a history of bloody suppression of street protests.