A man in his early 70s presented with stiffness and aching in the shoulder and pelvic girdles. His C reactive protein level was elevated at 116 mg/L, leading to an initial diagnosis of polymyalgia rheumatica. Treatment with prednisone at 20 mg/day provided limited improvement and relapses recurred despite concomitant immunosuppressive agents. Extensive investigations failed to reveal an underlying aetiology. Five years later, gross painless haematuria led to the detection of an invasive papillary urothelial carcinoma. A review of the staging CT scan revealed findings compatible with bilateral erosive sacroiliitis, which had developed since his initial presentation. Radical cystoprostatectomy provided temporary relief but after a further 9 months, symptoms relapsed, and metastatic spread was discovered. Paraneoplastic sacroiliitis is a rare clinical entity; and to the best of our knowledge, this is the first reported case associated with a solid tumour.