THE purpose of this study was focused on examining the influence of various physical wedge filters on the surface dose with various field sizes for 60Co γ-ray beam, which have been used to treat a variety of cancer worldwide, especially in developing countries. The percentage depth dose in build-up region for open and physical wedged beams were measured by a Markus chamber, which was irradiated by a 60Co beam. Irradiations were performed in a virtual water phantom at various depths for field sizes range from 4.5×4.5 up to 15×15 cm2. The polarity effect and the over-response correction factor were applied for Markus chamber. For open and wedge beams angles 15°,30° ,45° , and 60°, the percentage surface dose found to be 25.95%±0.17%, 24.59 % ± 0.06 %,24.08%±0.01% ,23.71%±0.05% , and 24.45%±0.11%, respectively, at 10×10 cm2 field size. So, their variations at same field were 1.36%,,2.24% 1.87% and 1.5% , respectively. The percentage surface dose decreased as the wedge angle increased for all field sizes. The percentage uncertainty for all data is 0.16%. The increase in the percentage dose at surface and build-up region with various field sizes for both open and wedged beams was due to electron contamination from the head of the treatment machine and air. However, a significant effect is seen for physical wedged beams, due to physical wedge eliminates secondary electrons at the same time generates new electrons.