HIV/AIDS affects the heart through different mechanisms. Before the advent of HIV/AIDS, cachexia had been established as a cause of cardiac morbidity. Interestingly when HIV/AIDS affects the heart, not much role is ascribed to cachexia; one of the major criteria for diagnosis. As most electrocardiographic (ECG) changes in HIV/AIDS are also seen in cachexia, it became necessary to look at the ECG changes in HIV/AIDS in relation to body mass index (BMI). This was to see if any relationship existed. One hundred, 78 and 80 full blown AIDS, HIV positive asymptomatic and HIV negative subjects underwent 12 lead resting ECG respectively. Their BMI were determined from the heights and weights. BMI was least in the first group and highest in the last group. The mean differences achieved statistical significance. Systolic and diastolic blood pressures significantly fell from HIV negative to the AIDS patients. This was as BMI fell. Systolic and diastolic blood pressures fall significantly with cachexia. The following indices on ECG: heart rate, corrected QT interval, ST segment depression and T wave inversion increased from the HIV negative to the full blown AIDS patients. This was also the direction of reduction in BMI. Since these ECG changes have long been known with cachexia, it is being suggested that the cachexia associated with HIV/AIDS contributes to the heart disease in them.