One of the factors influencing the release of active substance from the drug formulation is presence of polymeric substance resulting in increase of viscosity of eye drops. Diffusion of sodium cromoglycate from polyvinyl alcohol 1.4%, 3% solutions and hypromellose 1% aqueous solution was investigated using in vitro method and diffusion coefficients were evaluated. Release of sodium cromoglycate from polyvinyl alcohol 1.4%, 3% solutions and hypromellose 1% aqueous solution was slower than the release from aqueous solution of sodium cromoglycate. The sodium cromoglycate diffusion from ophthalmic vehicle process kinetics was influenced by viscosity of these solutions and nature of the used polymers. The diffusion process of sodium cromoglycate from 1.4% PVA solution was more intensive if compared to diffusion from 1% hypromellose solution. The influence of excipients on sodium cromoglycate diffusion from eye drop formulation was evaluated when polymeric solutions have been used as vehicles.