This article provides a review of the past and current literature on how neurotransmitter systems may influence gender differences in behavioral functioning and mental disorders. Serotonin and dopamine seemed to be strongly involved: both showed higher concentration in females; serotonin seemed to be more associated with anxiety and depression disorders, to have a better response to SSRI treatment among women, and also is associated with a different repertoire of behavior. Dopamine seemed to be more involved in addiction disorders, worse schizophrenia positive symptoms among men and better response to antipsychotic treatment in female sex. Furthermore, we provide a review of the literature on noradrenaline, glutamate and GABA.