Since Lapides reintroduced clean intermittent catheterization (CIC) in 1972, this procedure has been used routinely in individualized programmes for bladder evacuation in various bladder disorders. It has been suggested that in clinical practice hydrophilic catheters are preferable to non-coated catheters. In reviewing the literature on CIC, many of the reports were found to rely on data from non-randomized retrospective studies. In some recent prospective studies, involving a limited number of patients, hydrophilic and non-coated catheters have been evaluated and compared, especially with regard to bacteriuria and urethral irritation. The available data indicate that using hydrophilic catheters for CIC may induce lower rates of bacteriuria and long-term urethral complications such as urethral strictures. However, to reach a reliable conclusion about the supposed advantage of the hydrophilic catheters, there is a need for a prospective, randomized long-term multicentre study. It is important in such a study to define patient characteristics including age, gender, diagnosis of bladder dysfunction, reason for CIC, physical and mental handicap, manual dexterity and previous treatments. Effect parameters should include number of catheterizations, urinary tract infection, early and long-term urethral complications, patient satisfaction, preferences and dropout rates. It is obligatory to include factors such as cost-benefit and cost-effectiveness.