He received his medical training at Tufts University School of Medicine in Boston. After a post-doctoral clinical fellowship in cerebral blood flow at UCLA, he completed his internship and six years of neurosurgical training at the Hospital of the University of Pennsylvania. During his training at the University of Pennsylvania, he completed fellowships in brain tumor research and complex spinal surgery. In 2004, Dr. George J. Counelis joined the medical staff of John Muir Health and was chosen as the Medical Director of the Brain Tumor and Neuro-Oncology Program in 2008.