Actipol (0.007% paraaminobenzoic acid--PABA) is a new interferon (IFN) inductor. It was recently introduced into ophthalmological practice. Its efficiency in surface herpetic keratitis is proven. We studied the therapeutic efficiency of actipol in the treatment of stromal herpetic keratitis and compared the results with combined therapy with acyclovir (ACV) and leukocytic IFN. The main group (141 patients) were treated with actipol and the reference group (40 patients) with ACV ointment and leukocytic IFN. Local injections of actipol in combination with its instillations into the conjunctival sac led to cure of 67.3% patients with stromal herpetic keratitis; this treatment was more effective than combined local ACV + leukocytic IFN therapy (clinical cure in 45% cases). Epithelialization in the actipol group was observed 2 days sooner, infiltration resorption and clinical cure 4 days sooner than in the reference group. Relatively high visual acuity in the actipol group was presumably due to the reparogenic effect on the corneal stroma and antithrombotic, fibrinolytic, and antioxidant activity of PABA. Hence, actipol is an effective drug for the treatment of stromal herpetic keratitis, exerting virtually no side effects.