Dr. Tilles received his medical degree in 1990 from the University of California at San Diego after finishing is undergraduate work at Harvard in 1982.  He completed his internship and residency in Internal Medicine at the Oregon Health Sciences University in 1993 and his Allergy and Immunology fellowship at the National Jewish Center for Immunology and Respiratory Medicine in Denver in 1995. Dr. Tilles subsequently spent five years as an Assistant Professor of Medicine and Pediatrics and Director of the Allergy and Asthma Clinic at the Oregon Health Sciences University. He is board certified in Allergy and Immunology, and he has a special interest in difficult asthma and a unique syndrome called vocal cord dysfunction.

Dr. Tilles joined Northwest Asthma and Allergy Center in September, 2000 and is also Executive Director of ASTHMA Inc., a non-profit clinical research center.  He spends approximately one third of his time in ASTHMA Inc. and two thirds of his time seeing patients in clinic. He is also a past President of the Oregon Allergy Society and the Western Society of Allergy, Asthma, and Immunology, and served on the Board of Regents of the American College of Allergy, Asthma, and Immunology from 2003 to 2006.  In addition to his Joint Task Force for Practice Parameters work, he is also an Associate Editor of the Annals of Allergy, Asthma, and Immunology and Associate Editor of AllergyWatch.