Narrowband RF filtering is required for stabilization of optoelectronic oscillators and forced oscillators. An optical transversal filter is proposed to perform narrowband RF filtering in opto-electronic (OEO) oscillators by realizing a Mach-Zehnder interferometer (MZI) at RF frequency of 8.8GHz. This 1<sup>st</sup> order optical filter is realized utilizing various lengths of SMF-28 fiber and 3dB couplers to perform RF filtering in the optical domain. With proper delay length, arm amplitude balance, and filter implementation, a stable filter with large null depth can be achieved. A tuning of 33kHz/nm is also achieved using standard fiber dispersion at 1550nm. The phase noise measurements of standard OEO are performed using this transversal filter with excellent results.