Objectives: The main objective of the study is to the role of sialic acid in the treatment of prostate cancer in males after receiving radiotherapy. Methodology: 5.0 ml blood sample was taken from vein. Blood was further processed for the estimation of Sialic acid. Commercially available enzymatic kits of Randox were used. Blood was centrifuged at 4000 rpm for 10 minutes and serum was separated. Results: Neuraminidase is used for the hydrolytic breakage of sialic acid in the body. The data present in the table shows that there is a random change in the neuraminidase levels of prostate cancer. As it increases in those patients who received radiotherapy only one time. The value is 0.59±0.15 (pre) and 1.15±0.53 (post). But in those patients who recived radiotherapy twice the level become slightly decreases as 1.02±0.60 to 0.99±0.32. But the trend become changed in adjuvant radiotherapy. As the levels of neuraminidase become highly increases in adjuvant radiotherapy. Conclusion: It is concluded that sialic acid is one of the important marker of body for protecting the body against the effects of radiotherapy.