Rectal linitis plastica (RLP) is a circumferentially infiltrating intramural anaplastic carcinoma that results in a rigid constricted rectum with thickened walls. A long delay between the onset of symptoms and the diagnosis often occurs because RLP can mimic a lot of diseases and endoscopy and biopsies are often negative, owing to the fact that the mucosa is frequently unaffected in RLP. RLP secondary to bladder cancer is rarely described in the English literature. We present the first report of the MR features of secondary rectal linitis plastica from a bladder carcinoma. Two patients presented with changed bowel habits. All diagnostic tests were inconclusive. In both patients, pelvic T(2) weighted MR images revealed a double-layered thickening of the rectal wall with an inner isointense circumferential thickening of the submucosa and outer hypointense circumferential thickening of the muscular rectal wall. Based on MRI, further investigations were performed and secondary RLP was diagnosed. It is important to establish the diagnosis of RLP early because of its bad prognosis. The value of MRI in supporting the diagnosis of RLP should not be underestimated. As endoscopy plus biopsy can often be negative, we suggest that, if pelvic MRI shows a concentric double layered thickening of the rectal wall over a long segment, then the diagnosis of RLP should be considered. This should prompt further investigations either to confirm or rule out the diagnosis of RLP by performing endoscopy with deep rectal wall biopsies.