The results of pterygium excision were assessed in an open study following a double-blind study on the effect of after-treatment with Strontium 90 (Sr 90). The results of the treatment of more complicated pterygia with disturbances of ocular motility and reduced visual acuity were also assessed; the treatment consisted of pterygium excision, conjunctival flaps or keratoplasty, and in the case of symblepharon fornix reconstruction. Thirty-three eyes with pterygia which had not previously been operated on, were treated with the "bare sclera" operative technique in combination with Sr 90 irradiation. After this treatment there were no recurrences. In the group of 18 recurrent pterygia which were treated with the same technique, two recurrences were seen. These results of irradiation are in sharp contrast with the 67% chance of recurrence when the "bare sclera" technique is used alone. The results of the more complicated pterygium operations were also successful. Visual acuity, motility and appearance improved markedly or became normal. Recurrences were rare (0-6%).