Nima Rezaei (Persian: نیما رضایی; born in Qaem Shahr, Iran) is an Iranian scientist, a professor of clinical immunology and allergy at Tehran University of Medical Sciences, Associate Dean of International Affairs in the School of Medicine and the Director of Global Academic Program (GAP).

Nima Rezaei is the mastermind, founder and current president of the Universal Scientific Education and Research Network (USERN).

He initiated the Iranian Primary Immunodeficiency Diseases Registry (IPIDR) in 1999 under supervision of Professor Asghar Aghamohammadi, which earned him the best research project award in the 4th Avicenna festival.

He received a Short-term fellowship in Clinical Immunology and Bone Marrow Transplantation in Paediatric Immunology and Infectious Diseases & Northern Supra Regional Bone Marrow Transplant Unit for SCID and Related Disorders, Newcastle, UK, awarded by the ESID (European Society of Immunodeficiency).

Since 2015, he has held the positions of Vice Dean of International Affairs, School of Medicine, Tehran University of Medical Sciences, and Deputy President of Research Center for Immunodeficiencies.