Background: A potentially harmful complication of cardiac catheterization is the arteriovenous fistula. Precise knowledge of possible factors predisposing for acquisition of iatrogenic AV-fistulae could enable cardiologists to perform a risk stratification for cardiac patients prior to catheterization., Methods: Over a period of 2 years, 10,271 consecutive patients who underwent cardiac catheterization were included in this study. Auscultation of a new femoral bruit was followed by a duplex scan to confirm the suspected diagnosis of an AVF. Every patient was investigated on the day after catheterization., Results: The incidence of iatrogenic AVF was 0.86%. A multivariate regression analysis revealed five significant and independent risk factors: (1) procedural heparin dosage >or=12,500 IU (Odds Ratio (OR)=2.88), (2) coumadin therapy (OR=2.34), (3) puncture of the left groin (OR=2.21), (4) arterial hypertension (OR=1.86) and (5) female gender (OR=1.84). Coronary angioplasty (instead of diagnostic procedure), size and number of sheaths, age and body mass index did not significantly affect the incidence of AVF., Conclusions: The overall incidence of AV-fistulae following cardiac catheterization approximates 1%. Determination of significant risk factors will facilitate identification of patients at risk for iatrogenic arteriovenous fistulae prior to cardiac catheterization and thus help to develop strategies to reduce the incidence of AV-fistulae.