To test the possibility that shrimp pond rotifer resting eggs and hatched rotifers could transmit white spot syndrome virus (WSSV) to crayfish (Procambarus clarkii), we injected crayfish with rotifer and resting egg inocula that were WSSV-positive only by dot-blot analysis of PCR products. No crayfish became WSSV-positive after challenge with the resting egg inoculum. However, 1/15 crayfish became WSSV-positive after challenge with the rotifer inoculum. The results demonstrated that rotifers constitute a potential risk for WSSV transmission to crayfish and other cultivated crustaceans. However, the actual quantitative risk of transmission in an aquaculture setting depends on many variables that remain untested.