Saruplase is the non-glycosylated form of single chain urokinase-type plasminogen activator; it is produced by recombinant technique in Escherichia coli. Saruplase has plasminogen activating properties; it can also be cleaved to the potent plasminogen activator, double chain urokinase, resulting in the generation of plasmin. By means of a positive feedback mechanism, plasmin itself is able to cleave saruplase. At present, a bolus of 20 mg followed by an infusion of 60 mg over 1 h and preceded by a heparin bolus of 5000 U, represents the standard saruplase regimen. The PRIMI trial showed that this standard saruplase regimen achieves higher early patency rates than streptokinase. In the COMPASS trial, saruplase has been shown to be at least as effective as streptokinase, in terms of 30 day mortality. A comparative trial with urokinase (SUTAMI) resulted in similar late coronary patency. Saruplase has been tested against alteplase (100 mg over 180 min) in the SESAM trial. The early coronary patency and safety of both regimens were comparable. In a recent study, three bolus applications of saruplase have been investigated. A double bolus of 40 mg each given 30 min apart, is suggested to be more effective than standard saruplase, but concerns about safety remain. Further studies are required to assess safety of the double bolus regimen, and to compare saruplase with the gold-standard of frontloaded alteplase, or the equivalent double bolus reteplase regimen.