Retrolental fibroplasia (RLF), a proliferative vascular retinopathy found almost exclusively in premature infants, continues to occur despite careful attention to oxygen administration. Much has been learned about the etiology and mechanisms of RLF over the past 30 years, and it is hoped that technological and biological research will ultimately lead to its prevention. No treatment is of proven value for the proliferative stages of RLF, although photocoagulation and cryotherapy directed at destruction of neovascularization are under study. Surgical treatment may be of value in controlling associated problems, particularly retinal detachments.