In this paper we seek evidence for the participation of the idiotype-anti-idiotype network in the polyclonal B-cell activation (PBA) associated to malaria. For this purpose we tested by an immunoradiometric assay a panel of nine monoclonal antibodies (including seven anti-idiotype antibodies) against three different (plasmodial or non plasmodial) heteroantigens: the 307 synthetic peptide (an epitope of a P. falciparum hepatic stage specific antigen) the (NANP)4 synthetic peptide (a repetitive epitope of the circumsporozoite protein of the P. falciparum sporozoite surface), and dinitrophenyl (DNP) molecule coupled to bovine serum albumin (BSA). Besides the anti-TNP-DNP antibody, the ABPC48 idiotype (directed against beta polyfructosan a fragment of levan molecule) and one anti-idiotype antibody reacted with DNP-BSA. Two other anti-idiotype antibodies (directed against idiotypes of antibodies specific of beta poly-fructosan and phosphorylcholine) were positive against the (NANP)4 antigen. Three antibodies reacted with the 307 antigen which was also recognized by the ABPC48. One of these antibodies was positive to both P. falciparum peptides tested. These preliminary results suggest the existence of crossreactions between plasmodial antigens and idiotypes of antibodies directed against other heterologous antigens. Thus, malaria induced cross-reactive antibodies could act as hetero and/or auto-antibodies explaining, at least partially, the malaria associated PBA phenomenon and modulating the specific immune response during the course of the infection.