In a pilot double-blind, randomized, prospective controlled study the effectiveness and safety of 0.3% netilmicin ophthalmic solution were compared with those of 0.3% tobramycin in treating external bacterial ocular infections in 45 eligible patients. The treatment with both study medications resulted in a significant (p < 0.001, Wilcoxon test) reduction in the mean cumulative score of the signs and symptoms. However, no statistically significant differences were observed between the two groups. The clinical improvement rate was almost complete with either antibiotics. There was a statistically positive trend in the netilmicin group with regard to the microbiological improvement that was achieved in (87% of the netilmicin patients) compared with 77% of the tobramycin patients (77%). Antibiotic sensitivity revealed that 84% of the organisms isolated were sensitive to netilmicin whereas only 64% of them were sensitive to tobramycin. Only minor adverse events occurred in patients treated with either netilmicin or tobramycin. In conclusion, this study demonstrates that netilmicin is a promising new antibiotic for treating external ocular infections.