Six different immunisation regimes were used in an attempt to elevate the concentration of ovine IgE. The response was measured by a passive cutaneous anaphylaxis (PCA) test. These regimes included infection with Ascaris suum and the combination of infection and parenteral administration of Ascaris antigens and ovalbumin in adjuvants. The regime producing the highest titre of IgE was the combination of Ascaris infection with parenteral administration of Ascaris extract in Bordetella pertussis. This regime consistently produced a transient high titre (1:1280-1:2560) of serum IgE 9-12 days after immunisation. The response to ovalbumin was transient and the maximum PCA titre obtained was 1:10.