A method is described for the elicitation of substantial amounts of anti-hapten and anti-protein antibodies in ascitic fluids of individual mice of various strains. The method utilizes repeated i.p. inoculations of 0.5-mg quantities of antien in complete Freund's adjuvant. A high volume ratio of adjuvant to antigen solution, and the volume used per inoculation, were shown to be critical factors. Asctic fluids developed after three to five inoculations and were subsequently tapped repeatedly over a period of several weeks. All strains tested produced substantial amounts of anti-KLH antibodies, but marked differences were noted with respect to response to a hapten. Titers were enhanced in low responders by priming before the induction of ascites. The method is also useful for the production of “nonspecific” IgG and other serum components.