In 1998, Dr. O'Brien became a team physician for Elite Sports Medicine which Dr. O’Brien was responsible for over seeing the health of athletes on Long Island. In 1999, while employed by Concourse Plaza Medical Complex, formerly a sub-division of Bronx-Lebanon Hospital was the Medical Director for the Physical Medicine Department as well as a primary care physician in a physician shortage area of the Bronx. During his employment, Dr. O'Brien developed a pain clinic treating acute and chronic pain with variety modalities including Osteopathic Manual Medicine.

As an attending physician, Dr. O'Brien volunteered time educating medical students, interns, residents, and physician assistant students on how to integrate alternative medicine into traditional practices.

On September 11, 2001, "9-11," day of the horrific attack on our city, country and freedom, Dr. O'Brien volunteered and helped establish The Stuyvesant High School Triage Center located in lower Manhattan just fifty yards from the Twin Towers. This Triage Center was declared a make shift hospital by the New York City Police and Fire Surgeons. Under their supervision, Dr. O'Brien and his colleagues coordinated care for the FDNY, NYPD, NYC-EMS and PAPD at "GROUND HERO." For this, Dr. O'Brien received an award from the President of the United States, George W. Bush, Jr.

Currently, Dr. O'Brien practices family medicine in a physician shortage area located in the South Bronx Empowerment Zone. He also serves as a Police Surgeon for New York State, Amtrak and a physician for the National Emergency Response Team. Dr. O'Brien is a Team Physician for the United States Amateur Boxing Association and serves as the Medical Director / Health Advisor for Church Alive Community Church.

On March 27, 2004, Dr. O'Brien was presented by Bishop Dr. Timothy Birkett a Humanitarian Award for outstanding medical services.   In conjunction with Church Alive Community Church, Dr. O'Brien has developed a series of high quality community health education show called, “ASK DR. TOMMY O.” In September 2004, the Ask Dr. Tommy O Health Education Show received a Beta Award from Bronx Net Cablevision for “Best Health Educational Show”. In October of 2006, Dr. O'Brien received the honor of being inducted into the Cambridge Who's Who, as a lifetime member.  His selection was based on demonstrating excellence in his profession. 

On July 4, 2007, Dr. O'Brien was promoted to commanding officer for the New York Guard's 88th Brigade, Forward Medical Detachment, stationed in upper Manhattan. July 13, 2007, Cambridge Who’s Who proclaimed Dr. O'Brien Cambridge Professional of the Year representing Family Medicine. In September 2007, Dr. O'Brien was presented an award from United Bronx Parents, Inc. for exceptional Medical and Humane Services for providing medical care to the South Bronx Community.

"I am committed to making a difference." Dr. Tommy O

 

During his tenor at Freeport High School, Dr. O'Brien was a competitive athlete, a varsity letterman, Wall of Fame member for athletic excellence, and competed in large events such as the Junior Olympics as well as represented Team Long Island in the Empire State Games for three consecutive years. After graduating from Freeport High School, Dr. O'Brien focused all his attention on academia. In 1985, Dr. O'Brien was invited to represent the New York Athletic Club as a water polo team member. Dr. O'Brien received an Associate in Science and Bachelor of Science in Biology from Nassau Community College and New York Institute of Technology respectively.  Immediately thereafter, Dr. O'Brien enrolled and graduated from New York Institute of Technology graduate program with a Masters of Science in Clinical Nutrition.

Late 1989, Dr. O'Brien applied and was accepted to The University of Osteopathic Medicine and Health Science located in Iowa. In 1995, Dr. O'Brien returned to New York City to begin his Family Medicine Residency. Dr. O'Brien graduated from St. Barnabas Hospital Family Medicine Residency Program in 1998. During residency, Dr. O'Brien developed a medical instrument and on December 16, 2003, Dr. O'Brien was granted a United States Patent.