The important role of circular cylinders in improving the Savonius wind turbine performance was demonstrated experimentally in this study. This was carried out by placing circular cylinders in 3 (three) configurations, namely configuration-A: circular cylinder is placed in front of the returning blade with a constant distance S/D = 1.4; configuration-B: a circular cylinder is placed beside the advancing blade at various distances Y/D = 1.27, 1.42, 1.61, 1.82 and 2.00, and configuration-C: is a combination of the two configurations. The Savonius wind turbine used in this study is made of PVC pipe, which is split into two with a diameter of D = 165.2 mm and a height of H = 294.4 mm equipped with a shaft having a diameter (b) = 19 mm. In this experiment, the turbine torque is measured using a rope break dynamometer to obtain the power coefficient (CoP) and moment coefficient (Cm) as a function of the tip speed ratio (TSR). For a wind speed operated at 5 m/s, the results show that for configuration- A, the presence of a circular cylinder effectively improves the turbine performance, where the CoP of the turbine increases by about 19% at a TSR of close to 0.6 relative to a conventional turbine. As for configuration B, not all Y/D distances can improve turbine performance, but only at Y/D = 1.42 and 1.61. The highest increase in CoP was obtained at a distance of Y/D = 1.61, with an increase of more than 25% at TSR = 0.69 compared to a conventional turbine. On configuration-C, the circular cylinder installed at Y/D = 1.61 and 1.82 caused the improvement of the turbine performance, where Y/D = 1.61 gave an increase in CoP of about 27.8% at TSR of about 0.63 relative to the conventional turbine..