Background: Pre-interventional knowledge of arrhythmogenic substrate location may reduce interventional time and arrhythmias ablation risks. Magnetocardiographic Mapping (MCG) is a contactless method for noninvasive localization of intracardiac sources used for Three-Dimensional (3D) Electro-Anatomical Imaging (EAI) of arrhythmogenic substrates. The aim of this study was to assess the repeatability, precision, and accuracy of MCG in localizing dipolar sources in an unshielded environment. Methods: The phantom consisted of a rectangular plastic box filled with 0.9% NaCl saline solution. Multiple artificial current dipoles (6 mm length, 10 mA, 50 Hz) were induced with two a magnetic electro-catheters. The distance between two dipoles was constant. 30 seconds MCG recordings (bandwidth DC-200 Hz, 1 KHz sampling rate) were performed with 36 DC-SQUID sensors at distances between Sensors plane and Dipole Sources (SSD) decreasing from 18 to 9 cm. MCG localization was assessed by inverse solution based on the Equivalent Magnetic Dipole (EMD) model. Orthogonal fluoroscopic imaging, employing lead markers to correct for x-ray divergence effect, was used to define the 3D physical relative position of each dipole. MCG repeatability, precision and accuracy were evaluated. The correlation between precision, Goodness of Fit (GOF) of the EMD model and SSD was also analyzed. Results: Overall, optimal repeatability (Coefficient of Variation ± Standard Error of the Mean = 0.79 ± 0.43%, 3D absolute error = 0.26 ± 0.25 cm), average localization precision (1.13 ± 0.42 cm) and average accuracy (0.2 ± 0.13 cm) were found. Localization precision improved (0.87 ± 0.3 cm) with GOF of the model increasing above 73% and SSD lower than 14 cm. Conclusion: Contactless MCG provides optimal precision and accuracy in localizing dipolar sources, even when performed in an unshielded environment. By integrating source localization into cardiac 3D imaging by cardiac magnetic resonance, MCG is foreseen to provide both pre-interventional and intraoperative 3D-EAI of arrhythmogenic substrates.