Objective: To determine the frequency of undiagnosed ischemic heart disease in patients admitted with acute exacerbation of COPD (AECOPD). Methodology: This cross sectional study was done from 1st January to 31st December 2015 at Pulmonolgy Department of Khyber Teaching Hospital Peshawar on patients admitted with acute exacerbation of COPD. Ischemic heart disease was diagnosed if a patient was found to have unstable angina, myocardial infarction or had echo findings suggestive of ischemic cardiomyopathy or regional wall abnormality. Data was gathered on a structured proforma where demographics, history of common risk factors and presence of ischemic heart disease and it's further type was documented. Data entered on SPSS version 19 and analyzed. Results: A total of 412 patients were admitted with the diagnosis of AECOPD. Mean age of the study sample was 61.6±12.5 years, with 41% males. Frequency of undiagnosed ischemic heart disease was found to be 18%. Among them 47% had unstable angina, 23% had myocardial infarction and 30% had ischemic cardiomyopathy on echocardiography. Conclusion: One in five patients admitted with AECOPD had undiagnosed ischemic heart disease documented as ACS or ischaemic cardiomyopathy. [ABSTRACT FROM AUTHOR]