Anxiety is a neuropathlogical condition which disturbs the normal routine life and CNS function. Serotonin is well known neurotransmitter responsible for pathogenesis of neurological diseases such as epilepsy, migraine, multiple sclerosis and Parkinson's disease &neuropsychiatric diseases like depression, anxiety and stress. Malfunctioning of 5-HT receptor, 5-HT transporter and mutation in gene code for its synthesis may contribute to abnormal function of serotonin. Nigella sativa is most common herb use as medicinal plant .In present investigation aqueous extract of Nigella sativa given to rats exerts anxiolytic and hyperserotonergic effect by increasing serotonin level in rat brain. Significant anixolytic effects were observed in open filed box and elevated plus maze. All these findings proved that Nigella sativa can be beneficial to treat neurological behavior defect which is due to hypoactivity of serotonergic neuron in brain