After 45 years of surgical practice, Dr. Hasselgren stepped down from his clinical duties in July of 2018. He remains a member of the Section of Endocrine Surgery in the Department of Surgery at the Beth Israel Deaconess Medical Center. He continues to serve at Harvard Medical School as the George H.A. Clowes, Jr. Distinguished Professor of Surgery. The change in work obligations will make it possible for Dr. Hasselgren to devote more time to teaching, research, and administration.

During the last several years of his career, most surgical procedures performed by Dr. Hasselgren have been related to endocrine surgery, including thyroid, parathyroid, and adrenal gland procedures. In addition, he has performed a large number of breast and general surgery procedures throughout his career. In his role as Director of Endocrine Surgery 2002-2018, Dr. Hasselgren oversaw the academic, educational, and developmental activities in the Section of Endocrine Surgery in the Department of Surgery at the Beth Israel Deaconess Medical Center. These activities included a monthly surgery-endocrinology-pathology multi-disciplinary conference, an annual visiting professorship in endocrine surgery, and the maintenance of a prospective database in endocrine surgery. The prospective database, which continues to be managed by Dr. Hasselgren, presently contains information about more than 6,000 patients and will continue to be the basis for ongoing clinical research reports.