Nanocrystals of sodium tungstates were synthesized using a hydrothermal route in the presence of poly(sodium 4-styrenesulfonate) to control the size of the crystals at the time of their growth. The lengths of the nanorods varied significantly, ranging from 400 nm to 6 mu m, whereas the diameters varied only slightly, ranging from 200 to 270 urn. These results show that a polyelectrolyte with sulfonate effectively caps the specific crystal planes or provides steric hindrance upon crystal growth, providing control over the size of the nanocrystals by varying the polyelectrolyte concentration.