Check your score report. Your registration number is located on your score report and is usually a seven-digit number. Do not confuse it with your confirmation number, which was probably sent to you by email when you signed up for the exam. Your score report will come within 15 days of completing the computer-based exam or six weeks after taking the paper exam.
Contact ETS. You will not be able to find information online. You have to contact the office by phone from 7 a.m. to 8:45 p.m. EST at 1-609-771-7670 or 1-866-473-4373. You will have to provide your name, address, date of birth, test date, Social Security number and telephone number. Your registration number will not be given to any friends or family members.
Contact academic agencies. Many schools or fellowship agencies require your GRE registration number to verify your scores. If you had a score report sent to a particular school directly from ETS, contact that department and ask if they can provide you with the registration number. Perhaps you included the registration number on an application for a fellowship. If you have an electronic copy of the application, scan your computer files using keywords for your application to see if the GRE registration number appears.