In a prospective study 163 patients aged 17 years or less admitted to a children's hospital between April 1985 and December 1990 with traumatic hyphema were treated with tranexamic acid, 25 mg/kg given orally every 8 hours to a maximum of 1500 mg every 8 hours for 5 days. Secondary hemorrhage occurred in 5 patients (3%), none of whom had more than one rebleeding episode. In contrast, 24 (8%) of 316 patients aged 17 years or less admitted to the same hospital between January 1977 and March 1985 with traumatic hyphema who were not treated with antifibrinolytics had a secondary hemorrhage, several more than once, giving a rebleeding rate of 33/316 (10%). The results suggest that tranexamic acid reduces the incidence and number of secondary hemorrhages in children, without significant ocular or systemic side effects.