Introduction: Discovering the enzymes involved in steroid biosynthesis in the central nervous system and the ability of neurons and glial cells to produce steroids is one of the major findings of neurobiology over the last two decades. Unlike classical steroids, these neurosteroids influence neuronal function through direct interactions with neurotransmitter receptors at the cell surface. Conclusion: Extensive studies have shown diverse physiological and pharmacological effects for these compounds. Moreover, neurosteroids have been shown to be involved in different pathological procedures, including neurodegenerative and neuro inflammatory disorders as well as neuropsychiatric diseases. Herein, we will review different aspects of neurosteroid biosynthesis and functions as well as their involvement in the pathogenesis of brain diseases.