Twenty patients with presumptive herpetic iridocyclitis without active corneal inflammation received either topical idoxuridine 0.5% or acyclovir 3% ointment. The uveitis of all ten patients treated with acyclovir resolved within one to eight weeks. Four of ten patients treated with idoxuridine worsened but subsequently responded to topical prednisolone 0.3%. The pathogenesis of herpetic iridocyclitis is discussed with a literature review.