An innovative and scalable approach, health financing by microfinance institutions can expand existing health-financing options for the poor. We examined healthcare-seeking behavior, health costs and health-financing methods among microfinance clients in Bolivia, Benin and Burkina Faso. Health costs and lost productivity were substantial. Clients benefit from assistance, including health savings, health loans and health micro-insurance. Microfinance institutions offer advantages in developing health-financing options: global reach, expertise in loans and savings, and their mission to facilitate household financial stability. Health-financing products hold considerable potential but require careful design to optimize value and minimize risk to clients.