AbstractTwenty patients with dendritic keratitis were treated in a double‐blind analysis study with either phosphonoformate 3% or trifluorthymidine 1% drops. Nineteen cases were virologically confirmed. Follow‐up was performed until closure of the corneal lesion was registered and a pair comparison between both substances was made. Healing time was longer for phosphonoformate (7.16 days) than for trifluorthymidine (5.83 days). There was no significant difference between phosphonoformate and trifluorthymidine. One drug failure was registered in each series. No side effects were obser