A double-blind clinical trial was performed on 26 patients suffering from corneal ulcers of proven (i.e., culture-positive) bacterial etiology. After their recruitment, the subjects were randomly assigned to one of the following treatment protocols: (1) tobramycin (15 mg/ml) in saline applied at 1 drop/h or (2) tobramycin (15 mg/ml) in low-molecular-weight hyaluronic acid applied at 1 drop/h. The sample size was adjusted according to a type I error of 0.01 and type a II error of 0.05 for a minimal expected difference of 35%. The healing time was calculated from the beginning of treatment to the day on which a follow-up fluorescein test proved to be negative. The mean healing time (+/- SD) was 3.5 +/- 0.9 days in the sodium hyaluronate group and 5.9 +/- 1.5 days in the saline group (P less than 0.001). These results suggest that treatment with an antibiotic dissolved in low-molecular-weight sodium hyaluronate can further shorten the clinical course of a bacterial corneal ulcer.