Object This work presents a highly-accelerated, self-gated, free-breathing 3D cardiac cine MRI method for cardiac function assessment. Materials and Methods A golden-ratio profile based variable-density, pseudo-random, Cartesian undersampling scheme was implemented for continuous 3D data acquisition. Respiratory self-gating was achieved by deriving motion signal from the acquired MRI data. A multi-coil compressed sensing technique was employed to reconstruct 4D images (3D+time). 3D cardiac cine imaging with self-gating was compared to bellows gating and the clinical standard breath-held 2D cine imaging for evaluation of self-gating accuracy, image quality, and cardiac function in eight volunteers. Reproducibility of 3D imaging was assessed. Results Self-gated 3D imaging provided an image quality score of 3.4 ± 0.7 v.s. 4.0±0 with the 2D method (p=0.06). It determined left ventricular end-systolic volume as 42.4±11.5mL, end-diastolic volume as 111.1±24.7 mL, and ejection fraction as 62.0±3.1%, which were comparable to the 2D method, with bias±1.96×std of −0.8±7.5 mL (p=0.90), 2.6±3.3mL (p=0.84) and 1.4±6.4% (p=0.45) respectively. Conclusion The proposed 3D cardiac cine imaging method enables reliable respiratory self-gating performance with good reproducibility, and provides comparable image quality and functional measurements to 2D imaging, suggesting that self-gated, free-breathing 3D cardiac cine MRI framework is promising for improved patient comfort and cardiac MRI scan efficiency.