Serbian MP Zvonimir Stevic, 65, resigned on Tuesday after a video of him watching pornography on his mobile phone in parliament went viral, public broadcaster RTS reported.
The video shows Stevic looking at the pornographic film during a tense parliamentary debate on a possible deal with Kosovo, which took place last week.
Kosovo, a former province of Serbia, unilaterally declared its independence in 2008, a decade after a war between Serb forces and Albanian rebels.
Both Serbia and Kosovo are under pressure from Western countries to reach an agreement to normalize their diplomatic relations.
The leader of the ruling Serbian Progressive Party attacked Stevic for “watching a porno film” during the session, which also saw physical clashes between several lawmakers.
A native of Kosovo, Stevic is a member of the Socialist Party, which is part of the governing coalition. He announced his resignation after the video went viral.