Solid-phase microextraction (SPME) has been used as a suitable and efficient sample preparation techniques for determination of various analytes from complex matrices [1]. Combination of molecularly imprinted polymer (MIP) with SPME enhances the efficiency of the extraction process. Natural biopolymers have gained increased attention in recent years as a substitute for synthetic materials. Unique properties of natural biopolymers such as easy processing method, low cost, availability, nontoxicity, ecofriendly and sorption capacity of prompted the use these compounds. In this study, construction of a novel (SPME-MIP) fiber based on chitosan and glutaraldehyde as coating material composites combined with highperformance liquid chromatography with ultraviolet detector (HPLC-UV) were studied. Phenobarbital, a barbiturate derivative, is one of the most commonly prescribed epilepsy medications which was measured by the proposed method [2]. In this technique, the chitosan biopolymer, as a new coating fiber, was produced on the modified stainless-steel wire, using chitosan, glutaraldehyde and phenobarbital as functional monomer, cross-linker and template, respectively. For comparison, a non-imprinted polymer was created using the same procedure to evaluate fiber selectivity. The SPME-MIP fiber coating was characterized by field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR), and thermal gravimetric analysis (TGA). The efficiency of fiber was then improved by adjusting the impact of numerous factors such as; pH, extraction time, desorption time, desorption solvent, and stirring rate. Results showed that the proposed fiber has a linear range 0.01-4 µg mL−1 , and detection limit of 7.5 ng mL−1 . The average recoveries in the four concentration levels for the spiked river and well water samples were 95.7 and 95.3%, with relative standard deviations of 3.8 and 5.9% for single fiber and between fibers, respectively.