Objective: To compare oral voriconazole with placebo in addition to topical antifungals in the treatment of filamentous fungal keratitis. Design, Setting, and Participants: The Mycotic Ulcer Treatment Trial II (MUTT II), a multicenter, double-masked, placebo-controlled, randomized clinical trial, was conducted in India and Nepal, with 2133 individuals screened for inclusion. Patients with smear-positive filamentous fungal ulcers and visual acuity of 20/400 (logMAR 1.3) or worse were randomized to receive oral voriconazole vs oral placebo; all participants received topical antifungal eyedrops. The study was conducted from May 24, 2010, to November 23, 2015. All trial end points were analyzed on an intent-to-treat basis. Interventions: Study participants were randomized to receive oral voriconazole vs oral placebo; a voriconazole loading dose of 400 mg was administered twice daily for 24 hours, followed by a maintenance dose of 200 mg twice daily for 20 days, with dosing altered to weight based during the trial. All participants received topical voriconazole, 1%, and natamycin, 5%. Main Outcomes and Measures: The primary outcome of the trial was rate of corneal perforation or the need for therapeutic penetrating keratoplasty (TPK) within 3 months. Secondary outcomes included microbiologic cure at 6 days, rate of re-epithelialization, best-corrected visual acuity and infiltrate and/or scar size at 3 weeks and 3 months, and complication rates associated with voriconazole use. Results: A total of 2133 patients in India and Nepal with smear-positive ulcers were screened; of the 787 who were eligible, 240 (30.5%) were enrolled. Of the 119 patients (49.6%) in the oral voriconazole treatment group, 65 were male (54.6%), and the median age was 54 years (interquartile range, 42-62 years). Overall, no difference in the rate of corneal perforation or the need for TPK was determined for oral voriconazole vs placebo (hazard ratio, 0.82; 95% CI, 0.57-1.18; P = .29). In prespecified subgroup analyses comparing treatment effects among organism subgroups, there was some suggestion that Fusarium species might have a decreased rate of perforation or TPK in the oral voriconazole-treated arm; however, this was not a statistically significant finding after Holms-Sidák correction for multiple comparisons (effect coefficient, 0.49; 95% CI, 0.26-0.92; P = .03). Patients receiving oral voriconazole experienced a total of 58 adverse events (48.7%) compared with 28 adverse events (23.1%) in the placebo group (P < .001 after Holms-Sidák correction for multiple comparisons). Conclusions and Relevance: There appears to be no benefit to adding oral voriconazole to topical antifungal agents in the treatment of severe filamentous fungal ulcers. All patients in this study were enrolled in India and Nepal; therefore, it is possible that organisms in this region may exhibit characteristics different from those in other regions of the world. Trial Registration: clinicaltrials.gov Identifier: NCT00996736.