Twenty-two infants with "threshold" stage 3+ retinopathy of prematurity (ROP) were entered into a prospective, randomized clinical trial to compare the efficacy of transscleral cryotherapy versus laser photocoagulation delivered by the indirect ophthalmoscope. Eighteen infants have been followed for at least 3 months. Fifteen of 16 eyes randomized to laser and 9 of 12 eyes randomized to cryotherapy showed regression. The results suggest that laser therapy is as effective as cryotherapy in the treatment of ROP (P = 0.285).