A Request for Evidence (RFE) is a detailed, written request sent from the U.S. Citizenship and Immigration Services (USCIS) to a visa applicant. In a Request for Evidence, the USCIS may ask the visa applicant to provide additional documents in order to support or establish their eligibility for a visa. Responding properly to a request for evidence is crucial for the success of any visa applicant. A failure to respond to the RFE, or responding with the wrong documents, can cause delays or even a rejection of the visa application.