Macrolide antibiotics are effective in eradication of C. pneumoniae from atherosclerotic plaques. Two small trials showed significant beneficial effects of macrolides on cardiovascular morbidity in patients with ACS. To corroborate and extend these findings, we undertook a randomised, placebo-controlled trial with clarithromycin in patients with stable CHD in order to test the hypothesis that intervention with a macrolide would reduce cardiovascular risk with regard to mortality and morbidity.