Molecular imprinting technology is a rapidly developing technique for the preparation of polymers having specific molecular recognition properties for a given compound,its analogues or for a single enantiomer. A variety of applications of molecularly imprinted polymers (MIPs) have been already investigated. Preparation of artificial antibodies, using in solid-phase extraction process, application as chromatographic stationary phases, and fabricating of selective electrochemical sensors are among these applications [4]. Phenobarbital (PB) is one of the oldest known anticonvulsant [2]. Selective determination of this compound is important because its toxic effects [3].Furthermore, the concentration of PB in blood is critical and must be accurately controlled. The possibility of metabolization of PB in the liver is a menace for human health.This communication intends to report the preparation of an electrochemical sensor based upon a MIP fabricated by polyaniline/graphene oxide nanocomposite. This composite was characterized by field emission scanning electron microscopy (FESEM), electron diffraction X-ray (EDX) and thermal gravimetric analysis (TGA). The prepared MIP was used for modification of carbon paste electrodes to fabricate a selective PB electrochemical sensor. Electrochemical behavior of PB on the investigated sensor and the optimization of the parameters affecting the PB determination with respect to the aqueous solution conditions and the electrode composition, were followed by cyclic voltammetry (CV). The obtained cyclic voltammograms of PB, showed a peak at about 0.2 V vs. saturated calomel electrode. It was shown that the anodic peak current increased linearly with PB concentration in the range of 40-400 (R2 = 0.89) g/L with the corresponding RSD 4.104 (for a solution of 10 g/L) and 0.6% (for a solution of 400 g/L), respectively. The selectivity of the proposed sensor was tested by determination of PB in the presence of relative barbiturate compounds. The developed electrode was applied for determination of PB in some real samples.