O'Callahan, Cliff, M.D., Ph.D.

Senior Faculty Pediatrician – Middletown Office


Southern Connecticut State University
New Haven, Connecticut

Graduate School

University of Health Sciences/The Chicago Medical School
North Chicago, Illinois
Doctorate in Biochemistry

Medical School

University of Health Sciences/The Chicago Medical School
North Chicago, Illinois


University of Washington/ Children’s Hospital and Regional Medical Center
Seattle, Washington


American Board of Pediatrics


Associate Professor
University of Connecticut

Assistant Professor
Quinnipiac University

Assistant Clinical Professor
Yale University

O'Callahan Casual

Cliff O’Callahan is the father of three young men and lives in Guilford, CT. He also happens to be the Chair of Pediatrics and the Director of Nurseries at Middlesex Health and it's Family Medicine Residency Program.

Born in Seattle, Cliff grew up in Ballycotton, County Cork, Ireland – a little fishing and farming village. He went to university at Southern Connecticut State University and then completed a MD/PhD program at the Chicago Medical School before returning to Seattle for his pediatric residency.

For the next three years Cliff lived and worked in Central America, first in the Guatemalan refugee camps in Mexico and then creating a community health program in the northern jungle region of Guatemala, the Petén.  Upon returning to the U.S., he worked for the Puyallup tribe of Indians in Tacoma, Washington as their first Pediatrician and public health physician, and was the Indian Health Service’s Maternal-Child Health coordinator for the Northwest states.

Cliff and Leah moved to Connecticut in 2002 to raise their growing family around lots of other family, and he joined the residency program as a teacher and clinician.  He leads the residency’s Global & Community Health Track, and serves as Medical Advisor to the Middletown school system. His academic interests include breastfeeding and ankyloglossia. He is heavily involved in community health efforts directed towards under 5 year children related to behavioral, oral, and nutrition wellness through the community collaborative Opportunity Knocks, for which he is the Medical Advisor.

Cliff created and leads the Middlesex-Sayaxche Partnership, linking Middlesex with a Guatemalan rural district hospital and community health worker project. Cliff and Leah brought their family to Rwanda for the 2012-13 academic year where Cliff served as the senior Pediatrician advisor in the inaugural group of U.S. educators in the Rwandan Human Resources for Health project. He now brings a senior resident for a month long rotation in Kigali each January.

Cliff serves on the American Academy of Pediatrics Connecticut state chapter’s Board and is past-Chair of the national AAP Section Forum Management Multidisciplinary Committee, and the Section on International Child Health.  He served on the American Board of Pediatrics Global Health Task Force and was an AAP Survive & Thrive advisor.

What I like best about working at Middlesex...

I love the variety of clinical, community and research activities we can be involved with which fulfill our mission of serving our population and our residents. It is a stable, supportive, and innovative medical community.

My favorite thing to do with residents is...

I enjoy exposing our residents to the joy of working with youth of all ages and their parents, whether it be in the office, bringing them to a community meeting, a home visit, or Guatemala/Rwanda. It is powerful to witness the emergence of a resident's awareness of their place in the larger community.

What I do for fun...

I like to hike, sail, mountain bike, read and sleep! Hope to travel more and visit our sons as they move on into life!