Sigurður Guðmundsson became Iceland's Medical Director of Health in 1998. He graduated with a degree of licentiate in medicine from the University of Iceland in 1975, and a Ph.D. from the same school in 1993. In 1981, he received a degree in internal medicine from the University of Wisconsin in Madison, USA and a degree in infectious diseases from the same school in 1984.

He began working as an intern in Borgarspítali Hospital and Landspítali Hospital from 1975-1978, and later became a specialist in internal medicine and infectious diseases at hospitals in the USA and Iceland. He was a part-time teacher at the University of Iceland, University of Akureyri and the Technical College of Iceland, and an associate professor and then professor of internal medicine at the University of Iceland from 1989-1999. He was appointed Deputy Medical Director of Health in 1997 and then Medical Director of Health one year later.

Sigurður was for a time active in the Association of Medical Students and the Reykjavík Medical Association, and has worked on numerous committees on behalf of the medical departments of the University of Iceland, Borgarspítali Hospital, Landspítali Hospital, health care authorities, medical associations and various ministries. For many years, he sat on the editorial board of the Icelandic Medical Journal, and was on the board of the Association of Icelandic Doctors against nuclear proliferation from1985-1987.

Sigurður Guðmundsson and his wife, Sigríður Snæbjörnsdóttir, Managing Director of the Suðurnes Health Institution, were in Malawi in 2006-2007 where they worked under the auspices of the Icelandic International Development Agency.