Medication adherence is an effective approach to prevent HIV transmission. In Mozambique, a country with a generalized epidemic, the government has adopted Positive Prevention (PP) training for clinicians as part of its national strategy. Our study, conducted after trainings in five clinics, examined the understanding of trained health care staff and their patients about the importance of adherence to antiretroviral therapy (ART), a key element of PP. Interviews with trained clinicians (n = 31) and patients (n = 57) were conducted and analyzed. Clinicians and patients demonstrated an understanding that ART adherence could decrease HIV transmission. However, participants also highlighted the difficulties of adherence when patients had limited access to food. At the same time that treatment as prevention awareness was increasing, poverty and widespread food insecurity were barriers to taking medications. In Mozambique, the full benefits of treatment as prevention may not be realized without adequate access to food.