On September 27, 2002, this report was posted on the MMWR website (http://www.cdc.gov/mmwr). CDC, the Food and Drug Administration (FDA), the Health Resources and Services Administration (HRSA), and state and local health departments continue to investigate West Nile virus (WNV) infections in recipients of organ transplantation and blood transfusion. This report summarizes two investigations of Michigan recipients of blood products, one of whom also received a liver transplant. Both persons tested positive for WNV infection after receiving blood products derived from a single blood donation subsequently found to have evidence of WNV. These investigations provide further evidence that WNV is transmitted through blood transfusion.