Mitochondria have a fundamental role in both muscle physiology and pathology. Mitochondrial fusion and fission are important for energy metabolism, calcium homeostasis and cell death. However, the mechanisms underlying mitochondrial dynamics are poorly understood, especially in physiological models such as skeletal muscle. Here we evaluated mitochondrial fusion dynamics in human skeletal muscle cells (HUSMC). Skeletal muscle satellite cells were isolated from human muscle biopsies and were maintained and differentiated in cell culture. Mitochondrial fusion events were evaluated by confocal imaging of cells expressing mitochondria matrix targeted DsRed and matrix targeted or outer mitochondrial membrane (OMM) targeted photoactivatable-GFP. When we tagged the mitochondria in ∼20% of total cellular area with photoactivated-GFP, we found those mitochondria undergoing matrix fusion with a frequency of 1.3 ± 0.1 events/min/cell (n=70). Among the fusion events, 40% led to complete fusion and only 10% was followed by separation at the apparent fusion site within 20 to 40 seconds. Both complete and transient fusion events resulted mostly from longitudinal mergers, involving end to end interaction or from mergers of adjacent mitochondria in side to side orientation. Furthermore, we found that OMM and matrix fusion are sequential and separable steps, displaying 5.8 ± 1 seconds gap (n=10). Finally, we evaluated the mitochondrial fusion dynamics in HUSMC derived from both normal and malignant hyperthermia susceptible individuals. At resting state, no significant differences were found in the number of events or in their characteristics. Thus, mitochondrial fusion commonly occurs in HUSMC, and enables mixing of both soluble and integral membrane factors. This process would help to maintain the stability of mitochondrial metabolism. The relatively low frequency of the transient fusion is probably due to the parallel organization of the cytoskeletal tracks for mitochondria and to the limited mitochondrial motility.