Long-term retention of patients in the rapidly expanding antiretroviral programs against HIV/AIDS is essential for the success of these programs. Unfortunately, high percentages of patients in need of treatment are lost to follow up in resource-poor settings. From June 2006 to March 2007 269 HIV-infected pregnant women were screened for participation in a Prevention of Mother to Child Transmission (PMTCT) study in Tanga, Tanzania. Ninety-one women were referred to Care and Treatment Center (CTC) for monitoring and antiretroviral therapy regardless of inclusion in the PMTCT study. Both women and HIV-exposed children were traced at CTC from mid-February to mid-March 2008. Follow-up visits for all patients were examined. Only 10% (9/91) of the referred women were still attending CTC by February/March 2008 and 64% (58/91) never attended CTC. Not a single child could be traced at CTC. The largest loss of patients occurs between referral and the first attendance at CTC. Every effort must be made to clarify reasons for loss of patients at this point. Further, measures to improve patient retention must be increased as must initiatives to improve the ability to trace and retain children within the clinics.