We report the case of a female patient with seronegative lupus and predominant bladder and intestinal involvement in the form of interstitial cystitis and protein-losing enteropathy. This association is exceptional in the literature but may be underestimated because of frequent latency of interstitial cystitis. It may define a peculiar subgroup of lupus patients usually responsive to steroid therapy. In this case, only cyclophosphamide markedly improved the protein-losing enteropathy but did not influence the bladder disease.