Infection of inbred Strain 2 guinea pigs by subcutaneous or intradermal injection of fresh or cryopreserved living Onchocerca lienalis microfilariae, followed by a challenge intracorneal infection of microfilariae, resulted in serum and aqueous IgE antibody and in significant corneal inflammation. Systemic or intraocular infections given separately were not sufficient to elicit IgE antibody or ocular inflammation. When intravenous transfer of pooled spleen cell suspensions from systemically infected donors to normal syngeneic recipients was substituted for the course of systemic infections, a subsequent intracorneal challenge of cell transfer recipients with microfilariae produced serum and aqueous IgE antibody. Administration of diethylcarbamazine citrate to infected animals following the intracorneal challenge resulted in increased serum IgE antibody and in increased corneal inflammation.