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Dr Dennis Kellar

Meet Dennis F. Kellar, MD, FCCP, DABSM

Dr. Dennis Kellar is board certified in internal medicine, pulmonary medicine, critical care medicine, and sleep medicine. He received his bachelor’s degree in biology at the University of South Florida and his medical degree from Ross University School of Medicine.

Following his residency at Chicago's Cook County Hospital, Dr. Kellar completed his fellowship in pulmonary, critical care, and sleep medicine at Rush University Medical Center in Chicago, where he was chief fellow.

While Dr. Kellar formally established Northwest Pulmonary and Sleep Medicine in 2007, his vision for having a practice with internal medicine, pulmonary medicine, critical care medicine, and sleep medicine under one roof dates back to when he began his residency training. He has been ahead of the trends of post-acute hospital care management and essentially pioneered the comprehensive sleep clinic approach.

Dr. Kellar's patients find him to be warm and personable. He sees patients in our Crystal Lake and South Barrington offices.

A proud veteran of the U.S. Army 101st Airborne Division, Dr. Kellar participated in Operation Noble Eagle and Operation Enduring Freedom in 2003. He was awarded the Medal-M and promoted to Major in 2005. Dr. Kellar is married to a local pediatrician and has five children. He enjoys flying as well as all types of water sports.

Board Certifications

  • Internal Medicine
  • Pulmonary Medicine
  • Critical Care Medicine
  • Sleep Medicine


  • Assistant Professor of Clinical Medicine, University of Illinois
  • Fellow, American College of Chest Physicians (FCCP)
  • Diplomate, American Board of Sleep Medicine (DABSM)
  • Society of Critical Care Medicine
  • American Thoracic Society
  • American College of Physicians
  • American Academy of Sleep Medicine
  • American Medical Association

Current Hospital Affiliations

For expert care of sleep disorders and breathing issues, call Northwest Pulmonary and Sleep Medicine at (815) 477-7350 or request an appointment online today. We have two convenient locations in Crystal Lake and South Barrington, Illinois.