Introduction: It is hypothesized that IgM antibodies to oxidized LDL are anti‐atherogenic. Myeloperoxidase from plaque‐infiltrating neutrophils catalyzes the production of hypochlorite (HOCl), which oxidizes LDL. Here we study the IgM response to HOCl‐modified LDL in comparison to titers of T15 clonotypic natural antibodies. Methods: Plasma of LDLR−/− mice fed a normal chow or high‐fat diet was obtained after 6 and 16 weeks. The IgM responses to HOCl‐modified LDL and T15 clonotypic natural IgM antibodies were measured by ELISA. Results: The IgM levels in response to HOCl‐modified LDL increased dramatically in the atherosclerotic group after introduction of the high‐fat diet, but not in mice on normal chow. The natural IgM T15 clonotypic antibody titers revealed a more moderate increase during atherogenesis. Conclusion: Our results show that during atherogenesis there is a strong induction of IgM antibodies to HOCl‐modified LDL particles. Whether these induced IgM antibodies are pro‐ or anti‐atherogenic remains to be established.