Background: Cardiovascular diseases are a leading cause of global mortality, underscoring the need for practical diagnostic tools like electrocardiography (ECG). While traditional 12-lead ECGs are comprehensive, they are often costly and lack portability. The Hamrah Doctor ECGMOBILE 3L, a 5-lead portable ECG device, presents a more accessible alternative. This study evaluates its agreement with the standard 12-lead ECG. Methods: A prospective study was conducted with 100 patients admitted to a Cardiac Care Unit (CCU). Each patient underwent ECG recordings using both the standard 12-lead ECG and the Hamrah Doctor ECGMOBILE 3L device. Interval duration measurements were compared between the two devices. Statistical analysis included paired t-tests and linear regression to assess agreement. Results: The 5-lead mobile ECG demonstrated strong agreement with the 12-lead ECG, with correlations exceeding 91% across all intervals. Minor differences in IDMs and heart rates were attributed to the sequential, rather than simultaneous, recording of ECGs. Some morphological differences, particularly in T-wave inversions, were noted but were likely due to recording conditions. Conclusion: The Hamrah Doctor ECGMOBILE 3L reliably captures ECG readings comparable to the standard 12-lead ECG. While it does not replace the 12-lead ECG, its portability, ease of use, and accessibility make it a valuable tool for continuous cardiac monitoring, especially in telemedicine and rural healthcare settings.