Dennis Jirsch studied Medicine at the University of Alberta after which he spent four years as a Medical Research Council Fellow, obtaining MSc and PhD research degrees. He subsequently completed general surgical training at the Gallie Program in Toronto and was a surgeon at St. Michael's Hospital for a decade, before moving to establish a surgical department at the Credit Valley Hospital in Mississauga.

Dennis returned to Edmonton as Chief of Surgery at the Royal Alexandra Hospital in 1991. These were tempestuous times in health care, and Dennis went on to try his hand at administration, working for some years as regional medical director and Provincial Medical Care Consultant before, relievedly, returning to clinical practice.

Dennis retired from surgical practice in 2015, but continues to write about issues pertinent to physicians for the AMA.