The synthesis of efficient photoluminescent quantum dots via growth on a DNA template is reported for the first time. The nanoparticles emit in the second biological window of 1.050-1200 nm with quantum efficiencies of 11.5 +/- 1% in aqueous solution, and are stable for over a week in blood plasma at 37 degrees C. The Figure shows an energy-filtered TEM image of PbS nanocrystals (Pb: orange; P in DNA: green).