Background Atherosclerotic lesions are mainly composed of macrophages and T lymphocytes. Specific T helper type 1 (Th1) cytokines and interferon gamma (IFN-γ) inducible chemokines have been shown to be present in these lesions, modulating the local immunologic response. To explore whether this increase in Th1 activity could also be detected in circulating cells indicating a systemic activation, we studied the peripheral expression of Th1 cytokines and chemokines in patients with coronary artery disease and controls. Methods and results Fifty patients with coronary artery disease (25 with unstable angina and 25 with stable angina) and 10 controls were studied. Serum interleukin (IL)-12 and IFN-γ and the expression of IFN-γ inducible chemokines IP-10, Mig and their receptor CXCR3 in peripheral cells were analyzed. Serum IL-12 and intracellular expression of IFN-γ were significantly elevated in patients with unstable angina. An enhanced expression of IFN-γ chemokines IP-10, Mig and CXCR3 in patients with stable angina was also observed. Conclusions This study demonstrates an increased systemic inflammatory activity in patients with coronary heart disease with a predominant Th1 response, particularly in patients with unstable angina, suggesting an important role played by this polarization in plaque formation and rupture.