Arterial thrombosis is the major reason for severe complications of coronary artery disease (CAD). Recently it has been suggested that the FXIII-A Val34Leu polymorphism, affecting clot stability, provides protection against thrombosis. Results published up to date implicate that there is a significant correlation between geographical area and the Leu34 allele prevalence and that its contribution to arterial thrombosis is different in different populations. The purpose of this study was to determine frequency of Leu34 allele in Croatian subjects as well as to estimate its association with a CAD. FXIII-A Val34Leu genotyping was carried out by real-time PCR method on the LightCycler using melting curve analysis with forward 5'-AACTTCCAGGACCGGCTTT-3' and reverse 5'-ACCCAGAGTGGTGGGGAA-3' primers. The Leu34 allele frequency in studied Croatian subjects was 24.3%. No significant differences were found in the prevalence of FXIII-A Val34Leu genotype or Leu34 allele distribution between studied subjects (P > 0.05). Carriage of the Leu34 allele was not significantly associated with CAD or MI risk reduction (P > 0.05). This is the first report that studies the prevalence of the Leu34 allele frequency in Croatian subjects and our results suggest that possession of the Leu 34 alele does not provide protection against MI.