This study investigated the usefulness of collagen plugging with VasoSeal in patients after PTCA compared to a control group having identical sheath dwell times and therefore comparable levels of anticoagulation. A total of 150 patients were enrolled in this prospective and randomized study. Sheaths were pulled at exactly 5 h after arterial puncture. Time to hemostasis and local complications were determined. There were no statistical differences in baseline characteristics. The mean time to hemostasis in the collagen group was significantly shorter (3 +/- 3 min) than that of the control group (17.4 +/- 7 min). At 24 h, 23% of the collagen group patients had a small, 1% a medium and 4% a large hematoma. In the control group, 32% had a small, 4% a medium sized, but no patient a large hematoma. After collagen, one patient developed a pseudoaneurysm needing vascular surgery. In the control group, no major complication occurred. Compared to patients with manual compression at an identical sheath dwell time and an identical level of anticoagulation, there was a significant reduction in time to hemostasis but no statistical difference regarding local complications. Although the incidence of medium or large hematoma was low, the trend towards a decreased risk of smaller hematomas seemed to be counterbalanced by an increased risk of larger hematomas.