Heat shock protein (Hsp) 27 expression in cardiomyocytes increases in response to ischaemia. The extracellular release of Hsp27 from cardiomyocytes is proportional to its intracellular levels.To assess the influence of significant coronary artery disease (CAD), which by definition results in chronic myocardial ischaemia, on blood serum levels of Hsp27.Blood serum levels of Hsp27 in 62 patients with at least 50% lumen diameter narrowing in at least one main epicardial coronary artery on angiography and in 21 controls with normal coronaries were measured.Patients with CAD tended to have higher serum level of Hsp27 than controls [0.463 (0.158-0.809) vs. 0.184 (0.099-0.337) ng/ml, p = 0.084]. Serum Hsp27 level in patients with CAD affecting more than a single vessel was significantly increased [0.529 (0.192-1.004) ng/ml] compared with controls (p = 0.035) and with one artery narrowed [0.276 (0.087-0.549) ng/ml, p = 0.041]. No correlation between Hsp27 serum levels and severity of coronary narrowings assessed by Gensini score was found (r = 0.21, p = 0.11).Serum level of Hsp27 seems to be a potential marker of myocardial ischaemia caused by advanced 2- or 3-vessel CAD.