Bipolar disorder is a debilitating mood disorder characterized by recurring episodes of mania and depression. It affects 2.6% of adults and has a lifetime prevalence among adults of 3.9%. Current mood stabilizers such as valproate are not always effective for and/or are not well tolerated by a large number of patients. Therefore there is a need to develop or identify more effective and less harmful treatment. Omega-3- fatty acids have been shown to alleviate bipolar disorder symptoms without the harmful side effects. Since depletion of myo-intracellular inositol is one of the mechanisms hypothesized by which mood stabilizers exert their therapeutic effect, the goal of this study was to determine the effects of the omega-3 fatty acids decosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on intracellular myo-inositol levels and the expression of the INO1 and INM1 genes. To do so, cells were grown in the presence and absence of DHA and EPA and myo-inositol was assayed in the cell extracts and gene expression determined by RT-PCR. Our results showed unlike valproate, the omega-3- fatty acids increased intracellular myo-inositol and decreased INO1 expression. We therefore conclude DHA and EPA may exert their therapeutic effect on bipolar disorder by mediating myo-inositol levels.