Bovine herpesvirus type 1 has two major immunogenic surface glycoproteins: a 90 kDa haemagglutinin and the 130 (74 + 54) kDa glycoprotein. These proteins were purified by rate zonal sucrose density gradient centrifugation after extraction with nonionic detergent Triton X-100. For the preparation of ISCOMs, the glycoproteins were further adsorbed during a second rate zonal centrifugation, to micelles of Quil A glycoside, already added to the gradient. Haemagglutinating peaks were collected and used as subunit vaccine in rabbits: groups of three animals were injected with 50, 10 and 5 micrograms protein. Seroconversion was followed by ELISA, haemagglutination inhibition, neutralizing and plaque reduction assays. ISCOMs and unadsorbed subunits were efficient in inducing neutralizing as well as haemagglutination inhibiting antibodies: ISCOMs gave a higher level of response. The efficiency demonstrated by ISCOMs suggests their potential as a subunit vaccine.