Mitochondria are the key organelles within the cells, they have dynamic, double membrane-bound structures with discrete DNA (mtDNA). Proteins related to mitochondrial dynamics processes such as fusion, fission, transportation, and mitophagy are contributing to many neurodegenerative disorders such as Parkinson's diseases, Alzheimer's diseases, etc. Over the past years, rotenone has been used as un inducer of parkinsonian conditions in well-recognized cell and animal model. Many studies have suggested the use of antioxidants to protect against neurodegenerative disorders like PD. Among these agents, Alpha-Lipoic Acid (ALA) has been shown a potent antioxidant by reducing the level of reactive oxygen spices. The present investigation was aimed to study the protective effect of ALA on cell viability and mitochondrial fusion genes expression in SH-SY5Y cells induced by rotenone. In the first stage of the study the effect of rotenone toxicity on the viability of SH-SY5Y cells was assessed by using the MTT technique. the Quantitative study of mfn1 and mfn2 gene expression was performed by Real-time PCR. Data were analyzed by one‐way ANOVA followed by Tukey’s post hoc test using GraphPad Prism software. The data obtained from MTT assay showed a significant decrease in the number of viable cells at concentrations of 2.5- and 5-μM of rotenone for 24 and 48 hours. Alpha-Lipoic Acid improved mitochondrial viability damaged induced by rotenone (p˂0.05). The results of qPCR showed that a significant decrease of mfn1 gene expression in presence of 5μM rotenone (p˂0.05). This reduction of mfn1 gene expression was significantly elevated in presence of 20-µM Alpha-Lipoic Acid (p˂0.05). Our results indicted Alpha-Lipoic Acid could improve the toxicity effect of rotenone in cell viability and in altered mitochondrial fusion genes expression.