Dr. Nancy L. Williams-Horak, MD. Dr. Nancy L. Williams-Horak, MD. Languages: English. Phone: (202) 877-6527. Fax: (202) 877-6565. Contact this Provider: (202) 877-6527. ... Find a Doctor Careers Patient Portal Make a Donation Billing & Insurance Classes & Events Contact Us Newsroom Live Well & Healthy Blog MedStar Health DocTalk Podcast ....