As of April 2015, the fax number for Express Scripts if ordering from within the United States is 1-877-895-1900. It is important to note that only a doctor can fax in a prescription to Express Scripts. A patient cannot fax in any prescription, even if a doctor signs for it.
In addition to faxing prescriptions, doctors can phone in prescriptions to Express Scripts by calling 1-877-283-3858, or can submit prescriptions by mail to Express Scripts, Inc., PO Box 52150, Phoenix, AZ, 85072. Express Scripts is a prescription plan for those who have government and union health plans, such as in the Armed Forces.