A blood test and a saliva test for antibody to hepatitis A virus (anti HAV) were offered to British travellers seeking human normal immunoglobulin (HNIG) prophylaxis. The specimens were tested by an IgG capture and a competitive radioimmunoassay (GACRIA, COMPRIA). By GACRIA 211 subjects were anti-HAV positive and 358 anti-HAV negative on both serum and saliva. 10 other seropositive subjects had weakly positive saliva reactions. There were three discrepant results. For the population investigated HNIG use could be minimised at no extra cost by first testing the saliva of those greater than 40 years old, frequent or long-stay travellers, those born in HAV endemic areas, and those with a history of jaundice. Of the 51% of travellers tested for these reasons 20% were anti-HAV positive. They made up 76% of all those with antibody.