Pursuant to a congressional request, GAO reviewed the Social Security Administration’s Office of Hearings and Appeals’ (OHA) use and selection of medical experts (ME) to provide testimony or evidence for disability hearings and cases. GAO found that: (1) OHA policy required the selection of such experts on a rotational basis by medical specialty, when possible; (2) when purchasing expert testimony, OHA did not ensure compliance with either its rotation policy or federal procurement policy; (3) medical experts were consulted in approximately 12 percent of all OHA hearings; (4) OHA lacked adequate controls at the hearing office level to ensure the fair selection of experts; (5) some administrative law judges requested medical experts by name; (6) repeated use of individual experts led to questions regarding the fairness of the hearings; and (7) in Chicago, recruitment efforts were insufficient to ensure the availability of more than one expert in high-demand medical specialties.