ObjectiveTo systematically review the association of interleukin-33 (IL-33) expression and coronary heart disease (CHD). MethodsWe searched The Cochrane Library, PubMed, EMbase, CBM, VIP, CNKI and WanFang Data up to June 30th, 2014, to collect case-control studies concerning the association of IL-33 expression with CHD. Two reviewers independently screened literature according the inclusion and exclusion criteria, extracted data and assessed the methodological quality of included studies; and then, meta-analysis was performed using the RevMan 5.2 software. ResultsSix case-control studies were included. The results of meta-analysis showed that:there were no significant differences in the levels of IL-33 between stable angina pectoris or ST-elevation myocardial infarction patients and healthy population (MD=-25.15, 95%CI -51.08 to 0.77, P=0.06; MD=-28.97, 95%CI -62.89 to 4.95, P=0.09). However, there were significant differences in the levels of IL-33 between unstable angina pectoris or non-ST-elevation myocardial infarction patients and healthy population (MD=-24.79, 95%CI -50.00 to 0.42, P=0.05; MD=-14.60, 95%CI -20.09 to -9.12, P<0.000 01). ConclusionIL-33 expression may be associated with unstable angina pectoris and non-ST-elevation myocardial infarction patients.