The effect of medroxyprogesterone acetate treatment in preventing or retarding corneal ulceration after alkali burns was studied in rabbits in an attempt to correlate dose and response. The eyes were treated for 21 days with a 0.01% or 1% suspension administered topically four times a day or medroxyprogesterone acetate, 4 mg or 30 mg, given subconjunctivally on alternate days. None of these regimens was noticeably effective, although at times there was a trend toward retarding ulceration. Thus, it was not possible to confirm earlier reports of substantial efficacy of medroxyprogesterone. Corneal stroma with epithelial defects and/or ulcers persistently showed infiltration with neutrophils in the superficial stroma within the epithelial defect, implicating the tears as the source of the inflammatory cells.