Lars Klareskog (1945 ) is a Swedish medical (immunologist, rheumatologist) known for research into the genetics of autoimmune diseases such as rheumatoid arthritis (RA).Klareskog received in 1974 his degree as a physician at the University of Uppsala , where he was graduated in 1978 (On the structure, function and tissue distribution of HLA-DR and Ia antigens). 1990 to 1993 he held the chair of Clinical Immunology at Uppsala University.

 After that, he had by 2012 the Department of Rheumatology at the Karolinska Institute and the Karolinska Hospital and was head of the Rheumatology Clinic and Research Group. Since 2008 he has been there also director of the Center for Molecular Medicine.He received Crafoord Prize in 2013 for their discoveries concerning the role of different genetic factors and their interactions with environmental factors in the pathogenesis, diagnosis and clinical management of rheumatoid arthritis.