Ninety-five sera from Chinese NPC patients in different stages of the disease, 38 sera from Chinese patients with other cancers, and 50 normal Chinese sera, were titrated for EBNA, VCA, EA and complement-fixing (CF/S) EBV-specific antibodies. The geometric mean (GMT) EBNA antibody titre of patients with NPC at stage I was found to be four times higher than that of normal individuals and increased in parallel with clinical deterioration. Antibody titres against EBNA did not correlate with either VCA or EA antibodies but, in general, correlated with CF/S antibodies. EA antibodies correlated relatively well with VCA antibodies and discriminated better than EBNA titre between NPC at stage I and controls.