An open-label study of 20 normal, healthy volunteers was conducted to determine the tear concentrations after topical ocular application of ciprofloxacin 0.3% ophthalmic solution (Ciloxan). Tear samples were collected on Schirmer tear strips at 30 min, 2, 3, and 4 h, and were analyzed for ciprofloxacin using reverse-phase high-performance liquid chromatography. The results of this study showed the mean concentration, 4 h after dosing of ciprofloxacin, to be 16.0 $mUg/ml with 95% confidence limits of 8.15 and 23.79. It is concluded that concentrations of ciprofloxacin in tears were significantly greater than the minimum inhibitory concentrations for 90% of strains tested commonly reported for a majority of potential pathogens (i.e., ≤2 $mU/ml) 4 h after a single application of ciprofloxacin ophthalmic solution 0.3%.