Universal Health Coverage, to meet the Sustainable Development Goal of ‘Health for All’, aims to increase the access of preventative and curative care services, particularly to the poor and vulnerable. However, the very provision of curative services by health providers in the primary care setting in low-income countries is considered one of the major drivers of antimicrobial resistance. The Zanzibar Ministry of Health introduced performance-based financing (PBF) in 2 of 10 Health Districts in July 2013. Payments to health facilities and staff were on a fee-for-service basis using ‘direct quality indicators’. Results of an evaluation of secondary data of two indicators, ‘treatment according to guidelines’ and ‘antibiotics prescribed according to guidelines’ from 31 Primary Health Care Units in the two PBF pilot districts are compared with 28 in non-PBF districts. The proportion of patients treated with an antibiotic not in accordance with treatment guidelines after the introduction of PBF fell to 2%, 6% and 5% in 2014, 2015 and 2016, respectively, compared with an increase from 25% (2013) to 31% (2014) and 22% (2015, 2016) in non-PBF facilities. The key take-home messages from this evaluation are firstly that ‘direct quality indicators’ to improve the use of treatment guidelines, introduced into a national PBF reform that includes financial incentives and rigorous verification of register entries, have the potential to significantly reduce inappropriate use of antibiotics in high population density settings in Africa. Secondly, for a sustained reduction in the overall proportion of unnecessary antibiotic prescriptions rigorous monitoring of health worker behaviour is required to address changes in prescribing practice. A well-designed and monitored PBF with ‘direct quality indicators’ has the potential to ensure that ‘Health for All’, in terms of increased access to primary health services is not synonymous with ‘antibiotics for all’.