Steven Blankaart (24 October 1650, Middelburg – 23 February 1704, Amsterdam) was a Dutch physician, iatrochemist, and entomologist, who worked on the same field as Jan Swammerdam. Blankaart proved the existence of a capillary system, as had been suggested by Leonardo da Vinci, by spouting up blood vessels, though he failed to realize the true significance of his findings. He is known for his development of injection techniques for this study and for writing the first Dutch book on child medicine. Blankaart translated works of John Mayow.