Efalizumab is a recombinant, humanized monoclonal anti-CD11a antibody used for the treatment of moderate to severe plaque psoriasis. Immune-mediated thrombocytopenia and anaemia have previously been reported with this therapy. We describe the first case of immune-mediated pancytopenia in a patient treated with efalizumab. Close monitoring of all blood cell counts is warranted in light of this case.