This article discusses specific issues related to the market access of biosimilars. Biopharmaceuticals are complex molecules produced by living cells. Copies of these medicines, called biosimilars, are not identical to their reference medicine and therefore specific regulatory requirements apply. When considering the use of biosimilars, the question of the degree of comparability between a biosimilar and the reference biopharmaceutical needs to be considered for registration, pricing and reimbursement purposes in addition to the cost issue. To date, many key concepts (like clinically meaningful differences) remain undefined and the question of the degree of comparability is not yet resolved.