Peter leads the Experimental Haematology department at the Leeds Institute of Cancer and Pathology and the Translational Haematology Research Group. He is also an Honorary Consultant Haematologist at Leeds Teaching Hospitals NHS Trust.

 Professor Hillmen qualified in Medicine at Leeds Medical School in 1985 and completed his general medical training in Leeds in 1988. He was a Haematology Registrar in Hammersmith Hospital, London between 1989 and 1990 before completing three years as a Wellcome Training Fellow based at the Royal Postgraduate Medical School (1991 to 1993) completing a PhD working on PNH under the supervision of Professor Lucio Luzzatto. He then moved back to Leeds as a Senior Registrar in Haematology, Yorkshire (1994 to 1996). He was appointed as a Consultant Haematologist Mid-Yorkshire Trust and Leeds General Infirmary in 1996 before moving to Leeds Teaching Hospitals NHS Trust in 2004. He was appointed as Professor of Experimental Haematology, University of Leeds in 2013.

Professor Hillmen has research interests in both paroxysmal nocturnal haemoglobinuria (PNH) and chronic lymphocytic leukaemia (CLL). Since 1990 he has continued to research into PNH that eventually led to the development of anti-complement therapy for PNH. He was the lead on the trials of eculizumab and now leads the National PNH Service based in Leeds and Kings. The National PNH service looks after over 300 patients with PNH and this provides a unique resource for continued research into the pathophysiology and therapy of PNH.