BACKGROUND: QT interval prolongation is one of the most feared adverse effects of Escitalopram (SSRI).The objective of the study was to quantify the impact of escitalopram on corrected QT interval (QTc) which is a risk marker for life threatening ventricular arrhythmia. AIMS & OBJECTIVE: To quantify the impact of escitalopram on corrected QT interval (QTc). MATERIAL & METHODS: This descriptive case series was done on three hundred consecutive patients (Age: 20-70 years) reporting with depression at psychiatry department of Services hospital, Lahore between 1st January 2018 to 30th June 2018. Written informed consent was taken and study was approved by ethical review committee. Resting ECG and transthoracic echocardiogram of all patients were done and QTc interval calculated using Bazett method. Baseline investigations including renal profile, liver function tests and serum electrolytes were also done. All patients were started on escitalopram (5mg). Patients already on any antidepressant or QTc prolonging drug, baseline QT prolongation (> 500ms), cardiac patients and patients with abnormal rhythm on ECG were excluded. Patients were followed up monthly for 6 months and dose of antidepressant was adjusted accordingly. At the end of six months patients were called for re-enrollment. Two hundred and sixty patients were found eligible for the study who were then divided into four categories depending upon the dose of antidepressant drug (5,10,15 and 20mg). Average increase of QTc interval was then calculated in each category. RESULTS: Among 260 patients, regarding mean age grouping and distribution was 5mg dose (52.62 ± 9.46 years), 10mg dose (50.52 ± 9.40 years), 15mg dose (52.62 ± 9.46 years) and 20 mg dose (50.52 ± 9.40 years); p value 0.283. Serum Potassium; 5mg dose (3.8mmol/L), 10mg dose (4.0mmol/L), 15 mg dose (3.9mmol/L) and 20mg dose (3.9mmol/L); p value 0.361.Serum Magnesium; 5mg dose (1.9mg/dl), 10mg dose (1.9mg/dl), 15 mg dose (2.1mg/dl) and 20mg dose(1.9mg/dl); p value 0.301. Serum calcium; 5mg dose (9.0mg/dl), 10mg dose (8.7mg/dl), 15 mg dose (8.9mg/dl) and 20mg dose(8.9mg/dl); p value 0.431. Baseline QTc; 5mg dose (414ms), 10mg dose (391ms), 15 mg dose (399ms) and 20mg dose(402ms); p value 0.212. Mean QTc prolongation; 5mg dose (3.8ms), 10mg dose (6.2ms), 15 mg dose (8.9ms) and 20mg dose(13.4ms). Maximum QTc prolongation in 5mg dose (4.7ms), 10mg dose (8.8ms), 15 mg dose (13.9) and 20mg dose (21.8ms). CONCLUSION: QT prolongation with escitalopram alone in non-cardiac normal QT patients is not significant enough to endanger the patient to life threatening ventricular arrhythmia.