Mice genetically selected for high (HL) or low (LL) antibody responsiveness to sheep erythrocytes (SE) also differed in the immune response to other antigens. We have studied in details the non-specific effect of the selection on responsiveness to bovine seralbumin (BSA) that is an antigen non cross-reacting with SE. BSA has been used either heat-aggregated (H-BSA) or alum-precipitated (Al-BSA). The characteristics of the response to H-BSA and to SE both injected intravenously were similar in several aspects: ranges of interline difference in agglutinin response were equivalent; minimal immunogenic doses were lower in HL than in LL mice. As for SE, the use of an adjuvant (Al-BSA) increased the response of LL more than that of HL mice, so the interline difference decreased. The interline difference between minimal immunogenic doses was weaker with Al-BSA than with H-BSA (100 times and 10,000 times respectively). The threshold dose for induction of immunologic memory was lower in the HL than in LL mice. For Al-BSA this threshold dose was higher than the minimal immunogenice dose in both lines; for H-BSA it was higher (in HL) or equal (in LL) to the minimal immunogenic dose. The results of this article confirm that the selective breeding for SE responsiveness has modified the antibody response to BSA in a similar way. The group of genes controlling the level of antibody response are also responsible for the induction of immunological memory.