A 67-year-old woman presented with signs of severe intraocular inflammation and secondary glaucoma. The initial diagnosis was uveitis, and an anterior chamber paracentesis with cytological study of the aspirate failed to establish an aetiological diagnosis. After three trabeculectomies had failed to control the intraocular pressure, the blind eye was enucleated. On histopathological examination a mucinous adenocarcinoma was found to cover diffusely the iris surface and to involve the ciliary body and peripheral choroid. The patient subsequently developed evidence of widespread metastatic disease and died shortly thereafter. Although a primary tumour was never found, histochemical and immunohistochemical studies of the enucleated eye suggested that the lesion originated in the gastrointestinal tract. In cases of intractable glaucoma and anterior chamber inflammation, metastatic carcinoma should be included in the differential diagnosis, and efforts should be made to substantiate the diagnosis by a systemic examination or a biopsy.