BACKGROUND: Acute coronary syndrome (ACS) is the clinical manifestation of acutely diminished coronary arterial blood supply. The rate of increase of intraventricular pressure during isovolumetric contraction (left ventricular dP/dt) represents the rate of change of pressure during ejection. OBJECTIVE: The aim of this study is to evaluate the usefulness of the rate of increase of intraventricular pressure during isovolumetric contraction (dP/dt) in assessment of left ventricular function in patients with acute coronary syndrome and its relation to certain clinical and echocardiographic features. PATIENTS AND METHODS: The study is a cross sectional study including 50 patients with an established diagnosis of acute coronary syndrome. The study was performed in Baghdad Teaching Hospital during the period between 2/2/2013 and 5/3/2014. History was taken from all patients and recoded using a specially prepared questionnaire paper. Left ventricular internal dimensions at end diastole (LVIDd) and end systole (LVIDs) were measured using M-mode echocardiography to asses left ventricular systolic function (ejection fraction). Pulse Doppler tracing of the transmitral flow velocities and tissue Doppler image (TDI) mitral annular velocities were obtained from the apical four-chamber view to assess left ventricular diastolic function. Doppler-derived dP/dt was determined from mitral regurgitation (MR) spectral flow RESULTS: The study included 50 patients (31 males and 19 females, mean age of 65.26 ± 5 years). Low dP/dt values were found in 42 patients (84%). Low dP/dt values were found more in the age group (51-60 yrs) (p value < 0.05). The mean age of patients with low dP/dt (<1000) was (65.62 ± 5yrs) and that of patients with normal dP/dt (≥ 1000) was (63.38 ± 5 yrs) with no significant difference (p value > 0.05). Low dP/dt value was significantly associated with smoking and positive family history and not significantly associated with male sex, hypertension, and diabetes mellitus. No significant association was found between low dP/dt value and type of presentation of acute coronary syndrome (p value > 0.05) or ejection fraction (p value > 0.05). It was significantly associated with LV diastolic dysfunction, left atrial size, left atrial pressure, and left ventricular size (p value < 0.05). CONCLUSION: The use of dP/dt is useful for evaluating left ventricular function in patients with acute coronary syndrome.