Serotonin syndrome, or serotonin toxicity, is a serious disorder attributable to exaggerated serotonergic function in the brain, most commonly after antidepressant overdose or after combining several psychotropic medications. Similar condition (serotonin syndrome-like behavior) can be evoked in animals experimentally, following administration of serotonergic drugs. In addition to pharmacological stimulation, some genetic and other factors may contribute to serotonin toxicity, prompting the need for new experimental genetic models relevant to this disorder. Here we discuss current problems and perspectives regarding genetic animal models of serotonin-related syndromes, and outline the potential utility of these models in experimental neurochemistry and clinical research.