It has previously been suggested that a single dose of magnesium citrate produces adequate cleansing of the bowel for barium enema examination. To determine whether such a regimen has any advantage over the widely used two doses of Picolax, a prospective randomized blinded trial was performed with over 100 patients allocated to each of the bowel preparation regimens. Radiographs were assessed for quality of mucosal coating, faecal residue and overall quality of bowel preparation. Patient compliance was good with both regimens. Normal daily activities were inconvenienced significantly more by the Picolax (P < 0.001), whereas the magnesium citrate (Citramag) caused more interruption of sleep (P < 0.01). Mucosal coating was similar with both regimens. There was more faecal residue and poorer overall bowel preparation with Citramag (P < 0.001), although diagnostic accuracy was only infrequently felt to be compromised as a result. Citramag may offer an alternative to Picolax in patients where minimal disruption to daily activities is desirable and where the detection of polyps is not critical.