Sexually transmitted infections and HIV spread fastest where there is poverty, powerlessness and social instability characteristic of refugee and internally displaced populations. This document, produced by The Reproductive Health for Refugees Consortium (RHRC), provides an introduction for humanitarian programme workers to issues of HIV and AIDS. It describes the status of the epidemic, means of transmission and factors that make refugee communities especially vulnerable. This is a basic introduction to transmission, prevention and care of HIV and is backed up by a list of key resources.