Objective: To compare the ocular comfort and tolerability of loteprednol etabonate 0.5%/tobramycin 0.3% (LE/T; Zylet*) with dexamethasone 0.1%/tobramycin 0.3% (DM/T; TobraDex†) in healthy volunteers. Research design and methods: In this multicenter, randomized, double-masked, parallel-group study, healthy volunteers (n = 306) were randomized to receive LE/T or DM/T four times per day for 28 days. Subjects recorded subjective ratings for seven comfort/tolerability parameters using an electronic patient diary (EPD). The primary endpoint was the difference at week 4 from the ratings of an artificial tear at baseline in comfort/tolerability parameters between treatment groups, using a noninferiority paradigm. Clinical trials registration: ClinicalTrials.gov, NCT 00532961. Results: The 97.5% confidence intervals for the lower bound were within -10 for all of the seven comfort/tolerability parameters evaluated (pain, stinging/burning, irritation, itchiness, foreign-body sensation, dryness, and light sensitivity). Secondary analysis revealed small but significant within-treatment differences in pain favoring LE/T over tears and in light sensitivity favoring tears over DM/T (p<0.01). Small between-treatment differences in the changes from baseline tear ratings to individual study visits favored LE/T for pain, stinging/ burning, irritation, itchiness, foreign-body sensation, and light sensitivity at visit 4 (p ≤ 0.04); for pain, stinging/burning, and foreign-body sensation at visit 5 (p ≤ 0.03), and for dryness and light sensitivity at visit 6 (p ≤ 0.05). Conclusions: LE/T satisfied all conditions of noninferiority to DM/T in comfort and tolerability. Subjects receiving LE/T were more likely to report better ocular comfort/tolerability ratings relative to baseline artificial tears than subjects receiving DM/T. Limitations: The study population consisted of healthy volunteers. © 2008 Informa UK Ltd. All rights reserved.