Antiretroviral medications can reduce rates of mother-to-child transmission of human immunodeficiency virus (HIV) to less than 5%. However, in 2011, only 57% of HIV-infected pregnant women in low- and middle-income countries received a World Health Organization (WHO)-recommended regimen for prevention of mother-to-child transmission (PMTCT), and an estimated 300,000 infants acquired HIV infection from their mothers in sub-Saharan Africa; 15,700 (5.2%) of these infants were born in Malawi. An important barrier to PMTCT in Malawi is the limited laboratory capacity for CD4 cell count, which is recommended by WHO to determine which antiretroviral medications to start. In the third quarter of 2011, the Malawi Ministry of Health (MOH) implemented an innovative approach (called "Option B+"), in which all HIV-infected pregnant and breastfeeding women are eligible for lifelong antiretroviral therapy (ART) regardless of CD4 count. Since that time, several countries (including Rwanda, Uganda, and Haiti) have adopted the Option B+ policy, and WHO was prompted to release a technical update in April 2012 describing the advantages and challenges of this approach as well as the need to evaluate country experiences with Option B+. Using data collected through routine program supervision, this report is the first to summarize Malawi's experience implementing Option B+ under the direction of the MOH and supported by the Office of the Global AIDS Coordinator (OGAC) through the President's Emergency Plan for AIDS Relief (PEPFAR). In Malawi, the number of pregnant and breastfeeding women started on ART per quarter increased by 748%, from 1,257 in the second quarter of 2011 (before Option B+ implementation) to 10,663 in the third quarter of 2012 (1 year after implementation). Of the 2,949 women who started ART under Option B+ in the third quarter of 2011 and did not transfer care, 2,267 (77%) continue to receive ART at 12 months; this retention rate is similar to the rate for all adults in the national program. Option B+ is an important innovation that could accelerate progress in Malawi and other countries toward the goal of eliminating mother-to-child transmission of HIV worldwide.