Abstract: An immunoadjuvant capable of producing secondary antibody responses as great as 50 to 60% of those obtained using Freund's complete adjuvant (FCA) which responses decline at a slow rate while not showing the disadvantages associated with FCA. The immunoadjuvant comprises an immunoadjuvant oil such as a mineral oil, squalene or squalane and a polycationic polyelectrolyte immunoadjuvant such as DEAE-Dextran or polyethyleneimine. The immunoadjuvant preferably comprises an emulsion having the oil in one phase and an aqueous solution of the polycationic polyelectrolyte in the other phases. Such immunoadjuvants are used with antigens, such as conjugates of hormones, e.g. luteinizing hormone releasing hormone, and an immunogenic protein.