Posterior subcapsular cataracts studied in 86 eyes of 86 patients transplanted for keratoconus were retrospectively studied. The follow-up period ranged between one and four years with a median of 18 months. Twenty-eight eyes developed posterior subcapsular cataracts. The development of posterior subcapsular cataracts was significantly related to the total cumulative steroid dose and the total time steroids were administered (p less than 0.01). Age, surgical technique, and rejection episodes could not be significantly correlated with development of a posterior cataract. The progression of the cataract appeared to be slow, and if topical steroids were discontinued the lens changes appeared to stabilize and progressed in only one patient. The effect of an early posterior subcapsular cataract on visual acuity was minimal in the early stages.