In this study we studied the efficacy of mitomycin in prevention of relapsing of in pterygium in 80 patients in Amir Kabir hospital of Arak. This research was a case-control analytic- experimental study that was performed prospectivity. We observed pastoperative patients was performed prospectivity. We observed postoperative patients (because of pterygium) during 6 months after surgery, Small size was about 80 ones. Case group received mitomycin. The sex, age and local residency were matched carefully in both groups. Due to Pv<0.0001, there is a significant relation between prescribing of mitomycin and decreased relapses of pterygium in patients. In case group relapsed was observed in 5% of patients but in another group it was about 86%.