Researchers in nanomedicine envision a time when molecular-scale computing devices could be embedded in our bodies to monitor health and treat diseases before they progress. The advantage of such computers, which would be made of biological materials, would lie in their ability to speak the biochemical language of life.  Several research groups have recently reported progress in this field. A team at the California Institute of Technology (California, USA) used DNA nanostructures called seesaw gates to construct logic circuits analogous to those used in microprocessors. When new DNA strands are added to the test tube as “input,” the solution undergoes a cascade of chemical interactions to release different DNA strands as “output.” In theory, the input could be a molecular indicator of a disease, and the output could be an appropriate therapeutic molecule. Subsequent to this advancement, the Caltech researchers built a DNA-based circuit that could play a simple memory game. A circuit with memory could, if integrated into living cells, recognize and treat complex diseases based on a series of biological clues. A team at Massachusetts Institute of Technology (Massachusetts, USA) designed an RNA-based circuit able to distinguish modified cancer cells from noncancerous cells and, more important, trigger the cancer cells to self-destruct.