All of our doctors at Gastroenterology Associates are Board Certified in Internal Medicine and Gastroenterology.

William C. Haynes, M.D.
A true West Texan, Dr. Haynes was raised in Merkel where watching his grandfather, Dr. Sadler practice medicine, he was influenced to become a physician.  He graduated from Cooper High School in Abilene.  He obtained his medical degree from the University of Texas Medical Branch at Galveston and continued with training internal medicine.  He attended the University of Arizona Veterans Administration Medical Center in Phoenix, Arizona.  

His wife Carol and three children are actively involved in the community.  Dr. Haynes enjoys golf when he gets the chance.

Steven K. Johnson, M.D.
Following in his Grandfather's and Great Grandfather's footsteps,
Dr. Johnson attended the University of Texas Southwestern Medical School in Dallas where he graduated first in his class.  He trained in internal medicine at Parkland Memorial Hospital.  He then went on to complete a fellowship in Gastroenterology at Baylor University Medical Center.  

Dr. Johnson and his wife, Donna moved to Abilene in 1995 to raise their three children.  Dr. Johnson enjoys woodworking and building models of historic sailing vessels.

Gary Roark, M.D.
Born in Graham, Texas, Dr. Roark received his medical degree from the University of Texas Medical Branch in Galveston and also his internal medicine.  His Gastroenterology fellowship was at the University of Utah.  He was Assistant Professor of Internal Medicine at the the University of Texas medical Branch.

His wife Linda works at Hendrick's Medical Center.  His three children are competitive tennis players and Dr. Roark is their biggest fan.

S.P Pathmanathan, M.D.
Dr. Pathmanathan comes to Abilene from Baltimore , Maryland where he has been an attending physician in gastroenterology since 1986.

He completed Internal medicine training at Baltimore General Hospital and completed a Fellowship in Gastroenterology at Providence Hospital in Southfield, Michigan.