The results of the combined use of Beta Irradiation, topical Thio-Tepa and dexamethasone in the post-operative treatment of pterygium in 169 patients (213 eyes) are reported. The recurrence rate has been evaluated statistically only in eyes with true pterygia, and for this purpose the material has been divided into 3 groups: group 1 includes all the bilateral cases who either had both eyes treated with Beta therapy or not, group 2 includes all the unilateral cases, and group 3 is made up of the total number of eyes operated. In the group comprising the bilateral cases, the recurrence rate was 2/60 in the eyes treated with Beta rays and 4/18 in the non-treated ones (P less than 0.10). In the group comprising the unilateral cases, the recurrence rate was 8/73 in the Beta rays treated eyes and 18/41 in the non-treated ones (P less than 0.025). When the total number of eyes was considered, the recurrence rate was 10/135 in the eyes treated with Beta rays and 22/61 in the non-treated ones (P less than 0.05). The difference in the recurrence rate between the eyes submitted to Beta therapy and those not submitted is considered statistically significant.