Objectives The aim of this paper is to describe regulatory guidelines for bioavailability and bioequivalence studies in procedures for granting marketing authorisation for generic ophthalmic medicinal products in the European Union. Materials and Methods Literature search was done by topic and subject of research, authors and journals, from general to specialized articles and guidelines relevant to the issues of this paper. The targeted search was carried out via the on-line databases such as ScienceDirect, PubMed, medicinal products database of the Agency for Medicinal Products and Medical Devices of Croatia. The regulatory guidelines have been detailed searched through the European Medicines Agency database. Results Ophthalmic medicinal products are most often formulated as topical eye drops for the treatment of anterior ocular disorders. Bioequivalence of generic medicinal product with the reference medicinal product must be demonstrated by appropriate bioavailability studies. Bioequivalence implies an absence of significant differences in the rate and extent of the availability of active substance from the pharmaceutical equivalent at the site of action. For generic ophthalmic medicinal product in the form of a solution having the same qualitative and quantitative composition as a reference medicinal product, it may be required to exempt from the bioequivalence study. In other ophthalmic dosage forms of equal qualitative and quantitative compositions as a reference medicinal product, bioequivalence needs to be established because production differences may affect eye-related bioavailability. Appropriate methods for determininig bioequivalence are missing for many ophthalmic dosage forms. There are currently no guidelines specifically designed to evaluate the bioavailability of the ophthalmic medicinal product. The development of a guideline on quality and equivalence of topical products is in process, which should include alternative in vitro and in vivo models and methods to predict therapeutic equivalence with reference medicinal products. The scope of that guidance should focus on product for cutaneous use, but also other routes. Conclusion The current algorithms for evaluating the bioavailability of the drug in the eye after topical ophthalmic administration are based on the determination of characteristic systemic pharmacokinetic parameters (Tmax, Cmax, AUC) taken from standard guidelines for determining the bioavailability of medicinal products intended to achieve systemic effect. They serve only as a temporary solution to the development and implementation of appropriate guidelines prepared specifically for the assessment of bioavailability of the drug in the eye. The systemic effect of topical medicinal products is considered undesirable and systemic pharmacokinetic parameters of topical ophthalmic medicinal products can be determined and considered only with a view to assessing the safety of medicinal product. Compared to the sampling of physiological fluids (blood, urine) for the purpose of bioavailability testing and determination of the bioequivalence, fluid and eye tissue sampling for the bioavailability of the medicinal products in the eye is highly invasive and complex. The procedure for granting marketing authorization for generic ophthalmic products is based on Article 32 of the Medicines Act (which is in accordance with Article 10(3) of Directive 2001/83/EC) because bioavailability testing can not demonstrate bioequivalence. Therefore such applications are called hybrid generic applications. A waiver of the need to provide equivalence data may be acceptable in the case of the eye drops solutions and for demonstrating therapeutic equivalence is necessary to prove the pharmaceutical equivalence. Therapeutic equivalence can be established when it is proven that the composition of the test product and the results of study product development are comparable to the reference product, including physical and chemical properties of the product. Minor differences in the excipient composition may be acceptable if appropriately justified.