It has been suggested that hyaluronidase when given subconjunctivally may increase the penetration of antibiotics such as penicillin into ocular fluids and tissues. Its effect on a synthetic penicillin, viz. ampicillin, has been evaluated here. Forty-eight New Zealand white rabbits were divided into two numerically equal groups. Group I received 62.5 mg ampicillin and Group I1 received 62.5 mg ampicillin + 30 T.R.U. of hyaluronidase.All injections were made subconjunctivally. Ampicillin levels in cornea, aqueous, vitreous and optic nerve were determined. The results suggest that hyaluronidase has no effect in increasing the intraocular penetration of antibiotics.