We describe a patient with rheumatoid arthritis (RA) who developed a nephrotic syndrome during treatment with a fully human recombinant monoclonal antibody against TNFalpha (adalimumab, Humira, Abbott). The proteinuria disappeared spontaneously after cessation of anti-TNFalpha treatment and relapsed after rechallenge, pointing to anti-TNFalpha as the culprit. Although renal biopsy disclosed a membranous glomerulopathy, the clinical picture was more compatible with minimal lesion glomerulopathy. The pathogenesis of this side effect is not clear; several mechanisms could in theory lead to these abnormalities.