The influence of pH, tonicity, preservatives, polymers and instilled drop size on the disposition of sodium cromoglycate, an agent used in the prophylaxis of vernal keratoconjunctivitis, in the tear chamber of the albino rabbit eye has been examined. Radiotracer techniques were used throughout. The initial decline in concentration in the tear chamber was found to be unaffected by the presence of preservatives, pH, and tonicity over the ranges studied. However, significant increases in the residence time of sodium cromoglycate in the precorneal area were noted when a smaller instilled drop size was used and when 5% polyvinyl alcohol (PVA) was added to the aqueous vehicle. Tissue uptake was found to be greatest in the conjunctiva, followed by the cornea, the iris-ciliary body and the aqueous humor. In both the conjunctiva and the cornea, the addition of 5% PVA produced an elevation in the peak concentration of sodium cromoglycate and an increase in the time at which the peak concentration was achieved, indicating improved drug delivery to these sites.