Atherosclerosis of coronary arteries is a main cause of ischaemic heart disease (IHD). Matrix metalloproteinases, a super-family of zink-dependent enzymes, which are involved in the pathogenesis of atherosclerosis by the activation of migration and proliferation of smooth muscle cells and by the induction of destabilization of atherosclerotic plaques. Some observations suggest that C(-1562)T polymorphism of matrix metalloproteinase-9 (MMP-9) promoter predisposes to multivessel IHD. Therefore, the aim of our study was to evaluate the association between C(-1562)T MMP-9 polymorphism and angiographically-documented coronary atheroclerosis in 110 patiens. Genomic DNA isolated from peripheral blood nuclear cells was amplified by PCR method with pair of primers flanking the polymorphic regions and subsequently MMP-9 genotypes were identified by amplicon digestion with Pac I restriction enzyme. The T(-1562) allel was idientified by gain of restriction site. There were 67 CC homozygotes and 43 carriers of T allele (41 CT + 2 TT). No differences has been found among patiens with various number of significantly stenotic (>50%) coronary arteries (group 0, 1, 2 and 3, respectlively) in genotype distribution, age, prevalance of arterial hypertension, and plasma concentrations of triglycerides, cholesterol and fibrinogen. However, in subjects younger < 50 years, the frequency of T(-1562) allele was significantly higher in IHD patients as compared with controls (group O). Results of our preliminary study suggest, that C(-1562)T MMP-9 transition is associated with premature IHD in Polish patients.