The accurate staging of bladder cancer by computed tomography (CT) can be hampered where a bowel loop lies in close proximity to a tumour and the resolution of the system is such that a clearly defined fat plane between tumour and bowel is not visible. This paper describes the use of post-micturition scanning in a case where bowel involvement by tumour was suspected on the initial scans but was subsequently shown to be absent on the post-micturition scans. This technique has the potential, in selected cases, to reduce a CT staging from T4 to T3 or less.