Siamak Yassemi (Persian: سیامک یاسمی) is an Iranian mathematician. He is a professor of mathematics at University of Tehran. He was the vice president of the University college of sciences at the University of Tehran for more than 3 years which ended in 2007. He was the head of the School of Mathematics at Institute for Research in Fundamental Sciences for more than two years until he resigned from his post in 2009. He started to act as the head of school of Mathematics, statistics and computer sciences at the University of Tehran in 2015.
He was born in Khorramshar, Iran.
Yassemi completed his PhD. under the supervision of Hans-Bjørn Foxby at the University of Copenhagen in 1994. He has since devoted a substantial part of his career to mathematical education.
In 2009 he received the Khwarizmi International Award in basic sciences and in the same year he received the COMSTECH international award. The title of the project that has won the prize was "Homological and Combinatorial Methods in Commutative Algebra". He was an associated member of the Abdus Salam International Centre for Theoretical Physics (Trieste-Italy) for eight years (1996–2004). He visited the Max-Planck-Institut für Mathematik (Bonn-Germany), the Institut des Hautes Études Scientifiques (Paris-France), and the Tata Institute of Fundamental Research (Mumbai-India) for several times.