In Loving Memory of

Dr. Marius Constantin Teodorescu

June 9, 1937 – October 5, 2026

It is with deep sorrow that we announce the passing of Dr. Marius Constantin Teodorescu, a remarkable man and a true inspiration to everyone who had the privilege of knowing him.

Marius was born on June 9, 1937, in Aiud, Romania, and transitioned out of this life on October 5, 2026. Throughout his 89 years, he touched many lives with his wisdom, humor, and unwavering spirit of perseverance.

Marius grew up in war-torn Romania, where his father served as an army officer during World War II. Following the communist takeover, his father was stripped of his property and forced to work in a coal mine. Ironically, because the communist system favored children of working-class families, his father’s occupation as a coal miner helped Marius gain admission to medical school, where he graduated among the top of his class.

A free spirit with an independent mind and a natural resistance to authority, Marius found the restrictions of communist Romania difficult to accept. Yet his determination and belief in a better life never wavered.

After graduating from medical school, Marius spent his first two years practicing medicine as a country doctor, serving as the sole physician in a small rural Romanian town. He subsequently passed a highly competitive examination and earned a position at the Cantacuzino Institute, one of Romania’s most prestigious scientific research institutions.

He had a brilliant mind and a thirst for knowledge. His fascination with immunology and scientific discovery would shape his life’s work. He loved his research at the Cantacuzino Institute and was fortunate to be surrounded by loving family and friends.

In 1975, the University of Illinois in Chicago invited him to join its faculty as a visiting assistant professor. He was beyond excited about the opportunity, although accepting it meant leaving his wife and children behind in Romania. What followed was a long and difficult fight to reunite his family in the United States. Through extraordinary persistence and sacrifice, he eventually brought his wife and daughter to Chicago, followed two years later by his young son, who had remained with his grandparents. In the years that followed, Marius helped many other relatives and friends come to America and build new lives.

Despite having graduated from medical school in Romania more than a decade earlier, he passed his medical examinations again, becoming a licensed physician in the United States while continuing his research and teaching.

Marius became a distinguished physician, scientist, educator, author, inventor, and entrepreneur. A rheumatologist and immunologist, he served as Professor Emeritus of Microbiology and Immunology at the University of Illinois College of Medicine in Chicago, where he devoted decades to teaching and medical research. He also cared for patients at the Veterans Affairs medical center in Chicago as well as at the University of Illinois medical center. His numerous publications, inventions, and contributions to autoimmune disease research earned him recognition and respect throughout the medical and scientific community.

In 1988, Marius’s vision led to the establishment of TheraTest Laboratories. With the help of dedicated colleagues, he built and led the company for over three decades, contributing to advances in autoimmune disease testing.

Beyond his professional achievements, Marius was a man of exceptional character. He possessed enduring optimism, intellectual curiosity, generosity of spirit, and a remarkable ability to see the good in others. He valued friendship, treated people with kindness and respect, and approached life’s challenges with quiet strength and determination. Despite his accomplishments, he remained humble, approachable, and genuinely interested in the lives of those around him.

An avid reader, he loved painting, good music, traveling, and discovering new places. He was always looking forward to his next adventure.

Marius had a lifelong passion for the mountains. As a young boy, he explored the Carpathian Mountains with his father, later continuing those adventures with his wife, Ana. After coming to America, he explored the Rocky Mountains and the Great Smoky Mountains. Never one to shy away from a new adventure, he even learned to downhill ski in his 50s. He returned to visit the Smokies for the last time in 2026, at age 89. The mountains always held a special place in his heart, representing the freedom, adventure, and love of nature that remained with him throughout his life.

He accomplished so many things in his amazing life, but of all those accomplishments, he wanted to be best remembered as a good husband, father, family man, and friend.

His remarkable life will forever be an inspiration, a testament to an indomitable spirit filled with curiosity and resilience. He will be missed by his family and friends, and he will always remind those who knew him to live life to the fullest: laugh, joke, have empathy for each other, do good, and always love your family. He left this legacy to all of us.

Today and forever, he flies free.

He is survived by his loving wife, Ana; his children, Oana and Mihai; his grandchildren, Brendon, Seraphim, and Adam; his brother, Valentin; his sister, Daniela and her husband, Stelian; and his sisters-in-law, Georgeta and Lucia.

We remember him with love, admiration, and gratitude for a life well lived.

A memorial service honoring Marius will be held on Saturday, October 24, 2026, from 12:00p.m. – 4:00p.m. From 12:00pm -12:30pm is welcoming and gathering then from 12:30pm to 1:30pm will be a memorial service, followed by a memorial luncheon from 2:00pm to 4:00pm at Cappetta’s West Suburban Funeral Home, 4920 Main Street, Downers Grove, Illinois 60515. For additional information, please call 630-852-8000 or visit westsuburbanfh.com.

In lieu of flowers, the family welcomes memorial contributions to the Arthritis Foundation in memory of Dr. Marius Teodorescu, whose life’s work was devoted to advancing the understanding and diagnosis of autoimmune diseases.

Donations may be made through the family’s memorial fundraising page:

https://fundraise.arthritis.org/campaigns/In-Loving-Memory-of-Dr–Marius-Teodorescu