Objective: complications of coronary stenting include thrombotic reocclusion and restenosis. In this study anticoagulation by the warfarin analogue phenprocoumon in combination with aspirin was compared to treatment with ticlopidine and aspirin. Hemostatic markers for thrombosis were measured in a subset of patients. Design: non-elective implantation of 322 Palmaz-Schatz coronary stents was performed in 293 patients. Treatment with either phenprocoumon (163 patients) or ticlopidine (130 patients) was administered in addition to aspirin. Postprocedural complications were analyzed and laboratory parameters of hemostasis were determined. All data were reviewed in a retrospective data analysis. Results: complete stent occlusion occurred in 17 patients (5.8%) within the first 15 days. Out of these 17 patients 15 were treated with phenprocoumon (9.2%) and two with ticlopidine (1.5%), ( P=0.05). Post-procedural complications in the two groups were the following: groin aneurysm 25.8 vs 7.7% ( P=0.0001), bleeding complications 11 vs 2.3% ( P=0.008) and post-stenting myocardial infarction 8.6 vs 1.5% ( P=0.0173). Parameters of thrombin activation and hemostasis were measured in 16 patients of the phenprocoumon group with five stent occlusions and 11 non-occlusive stents. Patients with stent occlusion had elevated levels of trothrombin fragments F1+2 (4.8±2.8 nmol/l) compared to patients with patent stents (0.8±0.4 nmol/l; P=0.03). Levels of thrombin-antithrombin TAT (22.2±13.7 μg/l vs 2.5± 0.5 μg/l; P<0.004), and fibrinogen (617.5±101.3 mg/dl vs 441.4±47.0 mg/dl; P=0.003) were increased in patients with stent occlusion. Patients with and without stent occlusion had elevated plasminogen activator inhibitor-1 (PAI-1) levels (mean 46.2±20.5 ng/ml) without significant difference between the two groups. Conclusion: post-stenting treatment with the platelet antagonist ticlopedine prevents acute and subacute stent occlusion more efficiently and is associated with fewer side effects compared to anticoagulation with phenprocoumon. F1+2 and TAT are useful markers for stent thrombosis but are not suitable for the prediction of stent occlusion. Fibrinogen, however, appears to be a risk factor for coronary stent occlusion.