Holter monitoring is a non-invasive diagnostic test used to continuously record the electrical activity of the heart over an extended period, typically 24 to 48 hours, A small, portable device called a Holter monitor is attached to the patient with adhesive electrodes placed on the chest. The device records the heart’s rhythm and rate while the patient goes about their normal daily activities, including eating, sleeping, working, and exercising. Holter monitoring is especially useful for detecting irregular heart rhythms (arrhythmias) that may not appear during a brief ECG performed in a clinic. It helps diagnose conditions such as atrial fibrillation, palpitations, unexplained dizziness, syncope (fainting), skipped beats, or episodes of rapid or slow heart rate. It also helps assess the effectiveness of medications, pacemakers, and other cardiac treatments. Appointment is mandatory. Trim chest hair if possible for better fixing of electrodes. Do not shower/ bathe after machine is fixed. Give a chart to record date, time, activity and symptoms during study. which helps the doctor correlate events with the recorded heart rhythm. The test is safe, painless, and provides valuable insight into heart function during real-life conditions, making it a key tool in cardiac evaluation and management.