In a prospective study the results of a pterygium excision in 54 patients (57 eyes) who underwent a superficial free conjunctival autograft (FCG) were compared to those of patients who were treated with postoperative 90Sr-irradiation. In 51 cases the minimum follow-up was six months, the maximum follow-up seven years. We divided the study up into a randomized part and an open part. In the randomized part, surgery of a primary pterygium was performed in 25 eyes, of which 16 were treated with a FCG and compared with 9 eyes with primary pterygium surgery and postoperative 90Sr beta-irradiation. In the same period 16 eyes were treated because of a recurrent pterygium: 8 with FCG and 8 with 90Sr-irradiation. In the open part of the study 16 eyes with primary pterygium were successively treated with FCG alone. The results showed in the randomized, as well as in the open study on primary surgery with a minimum follow-up of six month, one recurrence in each of the FCG-groups (2 out of 31 eyes = 6.4%), and no recurrences in the 90Sr-group (0%). In the randomized group of patients treated for a recurrent pterygium one recurrence developed in the FCG group (1 out of 8 eyes = 12.5%) and one in the 90Sr-group (1 out of 7 = 14.6%). Analysis of other clinical parameters showed that postoperative treatment with corticosteroids, nonsteroidal anti-inflammatory drugs, and artificial tears was necessary for a longer period in the FCG group than in the 90Sr-group.