Following a first career in aeronautical engineering, Dr Greenwood graduated in medicine in 1976.  After training in Manchester and London (Barts) he moved to Stevenage in 1988 to establish a new renal service.  He was Clinical Director of Renal Services based at Lister serving Hertfordshire and Bedfordshire for 20 years up to 2008.  He continues as a full-time clinical nephrologist in the NHS.

The Lister renal unit has a long history of innovation in dialysis and maintains a creditable output of original research.  His research interests include haemodiafiltration, home haemodialysis, non-dialytic conservative management and end-of-life issues.    He is a co- coordinator (UK) of the Dialysis Outcomes and Practice Patterns Study (DOPPS).  He has a busy international schedule of lectures and attendances at advisory boards..

Dr Greenwood was the President of the British Renal Society from 1997 to 2000, served on the External Reference Group of the Renal National Service Framework from 2001 to 2004 and was a founder member of the UK Kidney Alliance was Chair from 2003 to 2007.  Currently he is the clinical lead at the EoE SCG for home dialysis therapies and self-care development.