Yeast (Saccharomyces cerevisae) beta-1,3 glucans were used as adjuvant in a Vibrio damsela vaccine for turbot (Scophthalmus maximus L.). Turbot were injected with the adjuvant prior, at the same time and after the vaccine. Several immune parameters (index and rate of phagocytosis, passive haemolytic plaque numbers, and agglutinating antibody titers) were determined at different times postinoculation. The highest activity of all the immune parameters was obtained when glucans were injected after the bacterin. It is concluded that the sequence of glucan administration is critical when used as a vaccine adjuvant.