Schizophrenia (SZ) and bipolar disorder (BD) are two severe mental disorders with similar, but differing symptoms that effect the patient’s function, and treatment protocols. However, there is considerable overlap in their genetic, epigenetic and environmental risk factors. They also have similar heritability profiles, either within or between the disorders, with no significant difference between either gender of the subject or the parent. Many similarities are also shared between SZ and BD in regards to signalling pathways as maintaining homeostasis is of utmost importance for a healthy, functioning organism where any alterations to the norm may result in disease. Schizophrenia and bipolar disorder have both been associated with disturbed signalling of the dopamine, Wnt and GABA pathways – all of which play an important role in the nervous system. Dopamine regulates hormones, and thus changes in mood, and although dopamine signalling is aberrant in both of these disorders, mood stabilization by lithium is better for treating BD, while antipsychotic drugs are the standard option in SZ. Wnt is vital in neuronal development, and altered signalling also affects its downstream component β-catenin which regulates gene expression, while aberrant GABA signalling directly influences the function of neurons and signal transmission that has been shown to partake in the development of almost all mental illnesses. Therefore, further research and correlation studies between these two disorders may help us understand them better and to treat them accordingly.