OBJECTIVE--The reported success rates for angioplasty of occluded coronary arteries fall some way short of the success rates for angioplasty of sub-occlusive stenoses. Two angioplasty systems used in this setting were compared. DESIGN--A prospective randomised open study comparing the Magnarail system (Schneider) and the Omniflex system (Medtronic). SETTING--A regional cardiothoracic centre performing over 300 angioplasty procedures a year. PATIENTS AND METHODS--50 consecutive patients with occluded (thrombolysis in myocardial infarction study (TIMI) grade 0 or 1) arteries thought to be suitable for recanalisation were assigned to undergo angioplasty with either the Magnarail or Omniflex as the primary system. Twenty minutes of fluoroscopic screening was allowed with the primary randomised system before it was considered a failure. The other non-randomised system could then be used at the operators' discretion, and a further 20 minutes' screening was permitted. MAIN OUTCOME MEASURES--A patent coronary artery with a residual stenosis of < 50% with prompt distal opacification (TIMI grade 3 flow) and a reduction in collateral supply to the index artery. RESULTS--The overall success rate in recanalising occluded vessels was 72%-64% for the Magnarail system used as the primary system and 51.7% for the Omniflex (NS). The Magnarail was more successful in angioplasties of the right coronary artery (11/14 v 3/10, p = 0.02) and in mid and distal sites of occlusion (11/17 v 4/14, p < 0.05). There was a trend in favour of the Omniflex in the left anterior descending coronary artery. CONCLUSION--Both systems would seem to be suitable for angioplasty of occluded coronary arteries. The improved steerability of the Magnarail may be advantageous in distal occlusions and lesions in tortuous arteries. The relatively stiffer Omniflex may be superior for proximal occlusions. The study group was too small to confirm this unequivocally.