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Three-dimensional conformal radiotherapy 3DCRT used to deliver precise dose for breast cancer. This study compared the effect of peripheral dose by two treatment planning techniques: complete beam and half beam on planning target volume, homogeneity dose, and doses of heart, Right Lung, Left Lung, homogeneity, and conformity index in the target region. Fifty women with left breast cancer were included in this study. 3DCRT was used to produce maximum dose to target volume coverage, minimum dose to healthy tissues, two techniques used for supraclavicular area, whole breast area, with a single isocenter. Mean dose Gy for PTV was lower in complete beam than half beam (40.53 vs 41.44 Gy, respectively; p< 0.006). The prescribed dose for the two methods was 40.050 Gy and complete technique was more uniform dose distribution than half. No significant difference was noted by two techniques in CI both< 1. Mean heart dose was significantly improved in complete compared to half (4.76 vs. 3.73 Gy, p< 0.003). Both techniques showed heart dose exposure< 2.6 Gy. Similarly, the Left Lung V20 values were significantly better in half beam than complete beam (20.1 vs. 20.8 Gy respectively; p< 0.465), and There was insignificant difference between the complete and half technique. The mean dose of the Left Lung was significantly lower for complete compared to half beam (10.81 vs. 10.19 Gy respectively; p< 0.003), but with the right lung was significantly lower for half compared to complete beam (88.2 vs. 29.4, respectively; p< 0.001). Complete planning treatment showed better homogeneity compared to the half beam plans.