The Magnum/Magnarail system consists of "over-the-wire" balloon catheters and a 0.021 inch (0.53 mm) guide wire with a 1 mm olive-shaped tip. To compare it to conventional systems, 100 consecutive unselected patients with chronic total coronary occlusions were randomly assigned to one of two groups. If the balloon could not be placed within 20 minutes of fluoroscopy time with the allocated system, a crossover to the other system was imposed. The Magnum group comprised 50 patients and 52 occlusions, and the conventional group included 50 patients and 51 occlusions. There were no significant differences with regard to the length of the occlusions (Magnum 1.4 +/- 1.3 mm, conventional 1.6 +/- 1.7 mm) or the duration (Magnum 1.4 +/- 1.9 months, conventional 1.4 +/- 1.8 months). The primary success rate before crossover with the Magnum/Magnarail system was 67% versus 45% with conventional systems (p less than 0.05). The Magnum/Magnarail system as a second tool after crossover was successful in 11 of 28 patients (39%) versus 2 of 16 patient (12%) in whom success was achieved with a conventional system as a second tool (p less than 0.05). An increase in the creatine kinase level (more than twice normal) was seen in one patient (2%) in the Magnum/Magnarail group and none in the conventional group. Q wave infarctions were not seen. There was one in-hospital death (2%) in the conventional group. There were no significant differences with regard to the number of guiding and balloon catheters or fluoroscopy time. The Magnum/Magnarail system proved superior to conventional systems for balloon recanalization of chronic total coronary occlusions in terms of higher success rates.