The objective of this report was to establish a novel model for the study of ventricular fibrillation (VF) in humans. We adopted the established techniques of optical mapping to human ventricles for the first time to determine whether human VF is the result of wavebreaks and singularity point formation and is maintained by high frequency rotors and fibrillatory conduction. We describe the technique of acquiring optical signals in human hearts during VF, their characteristics and feasibility on possible analyses that could be performed for elucidating mechanisms of human VF. We used explanted hearts from five cardiomyopathic patients who underwent transplantation. The hearts were Langendorff-perfused with Tyrode's solution (95%O₂+5%CO₂) and the potentiometric dye Di-4-ANEPPS was injected as a bolus into the coronary circulation. The fluorescence was excited at 531nm ± 20nm with a 150 W halogen light source; the emission signal was long pass filtered at 610 nm and recorded with a mapping camera. The delta F/F varied between 2-12%. The average signal to noise ratio was 40 dB. The mean velocity of ventricular fibrillation wavefronts was 0.25±0.04 m/sec. The sub-millimetric spatial resolution (0.65-0.85 mm), activation mapping and transformation of the data to phase based analysis revealed re-entrant, colliding and fractionating wavefronts in human ventricular fibrillation. On many occasions the VF wavefronts were as large as the entire vertical length (8 cm) of the mapping field, suggesting that there a limited number of wavefronts on the human heart during VF. The phase transformation of the optical signals allowed the first demonstration ever of phase singularity point, wavebreaks and rotor formation in human VF. This method provides opportunities for potential analyses toward elucidating the mechanisms of ventricular fibrillation and defibrillation in humans.