A clean bowel environment is essential prior to radiological assessment of the colon. The objectives were to determine patient compliance and acceptability, physician satisfaction, overall clinical effectiveness and tolerability with the use of oral sodium phosphates (Fosfosoda) and polyethylene glycol solutions as bowel cleansing agents in a relatively large cohort of Spanish patients requiring radiologic examination of the colon. This was an observational survey involving 592 patients (> or =18 years and approximately 60% women) who received Fosfosoda or polyethylene glycol solutions according to data sheet instructions. Parameters measured included mucosal cleansing (presence of solid residues), patient acceptability (including any adverse effects to treatment) and compliance with the treatment regimen, and physician-rated satisfaction with the procedure. The date from the study demonstrated that Fosfosoda and polyethylene glycol solutions were found to be equally well tolerated in this study, although patients receiving Fosfosoda found it easier to complete the treatment regimen. Fosfosoda was significantly superior to polyethylene glycol solutions with regards to mucosal cleansing with 52% achieving an 'excellent' result compared with only 36% of the polyethylene glycol group (relative risk:1.43; 95% confidence interval: 1.12-1.82). Physician-rated assessment of the bowel cleansing procedure also significantly favored Fosfosoda (p = 0.014). In conclusion, while Fosfosoda and polyethylene glycol solutions were equally well tolerated when given to patients prior to radiologic examination of the colon, Fosfosoda was shown to be significantly more effective in terms of bowel cleansing. Based upon the available evidence this could provide significant cost benefit for Fosfosoda.