A retrospective record review was conducted for patients down referred to primary health care facilities between 2007 and 2009 to assess the rate and reported reasons for loss to follow-up among stable antiretroviral patients in a down-referral model of care in Johannesburg, South Africa. Missing patients were traced telephonically. Of 3361 patients down referred, 4.11% were lost to follow-up. Most patients who were lost to follow-up were lost at the transfer stage between initiation and maintenance sites. Decentralization and nurse management of ART should be prioritized to increase access to and retention in HIV/AIDS care.