The feasibility and safety of using hydrophilic guide wires were compared with those of standard guide wires for retrograde catheterization of aortic stenosis in a prospective randomised study. The performances of the guide wires were assessed by the time taken to catheterize the aortic valve (minutes) and the duration of radioscopy (minutes: grays). The success of the procedure was defined as presence of the guide in the left ventricle in less than 8 minutes. The two patient groups were comparable with respect to the severity of the aortic stenosis. Two failures of catheterisation were observed in the "standard guide wire" group compared with three failures with the hydrophilic guide wire. The mean catheterisation time of the "standard" group was 2.56 minutes compared with 3.12 minutes with the hydrophilic guide wire (p = 0.35 NS). This result was correlated with the duration of radioscopy and number of groups (respectively p = 0.18 NS and p = 0.5 NS). One case of tamponade and a transient ischaemic cerebral attack were observed in the "standard" group. This study does not show the hydrophilic guide wire to be superior to the standard guide wire for catheterisation of aortic stenosis. However, the hydrophilic guide wires were perfectly innocuous for this procedure.