Ultralow-power electronics for cardiac monitoring make possible the development of new light-weight and low-cost devices that are ideal for long-term medical measurements and home-based tele-monitoring services. Nowadays, these devices are seen as a critical technology for reducing health-care costs. In this paper, we present several methods for reducing power consumption while retaining the precision necessary for cardiac monitoring. In particular, we describe a micropower electrocardiograph, an ultralow-power pulse oximeter, an ultralow-power phonocardiograph, an integrated-circuit switched-capacitor model of the heart, and an ultracompact and efficient lithium-ion battery charger. These components are, to our knowledge, currently the most power-efficient or minimal-size designs present in the literature in each respective category.