During 1998-1999, an outbreak of Nipah virus encephalitis occurred in Malaysia. To assess the possibility of nosocomial transmission, 338 health care workers (HCWs) exposed and 288 HCWs unexposed to outbreak-related patients were surveyed, and their serum samples were tested for anti-Nipah virus antibody. Needlestick injuries were reported by 12 (3%) HCWs, mucosal surface exposure to body fluids by 39 (11%), and skin exposure to body fluids by 89 (25%). No encephalitis occurred in either group. Three exposed and no unexposed HCWs tested positive by EIA for IgG antibodies. It is likely that these 3 were false positives; no IgM response occurred, and the serum samples were negative for anti-Nipah virus neutralizing antibodies. The risk of nosocomial transmission of Nipah virus appears to be low; however, given the high case-fatality rate and the presence of virus in respiratory secretions and urine of some patients, standard and droplet infection-control practices should be maintained with these patients.